1,272 research outputs found
Novel MCM Interconnection Analysis Using Capacitive Charge Generation (CCG)
A new SEM technique, Capacitive Charge Generation (CCG), has been developed to rapidly image MCM interconnection continuity. The new technique uses low primary electron beam energies (< 2.0 keV), very high beam currents (>100 nA), and fast electron beam scan rates (>5 frames/second) to probe buried conductors in MCMS. For these conditions, new surface charging effects have been observed that enable examination of conductors under thick insulating layers. CCG has been applied to conductors covered by over 90 {mu}m of polymer dielectric. The physics of CCG signal generation and applications for MCM failure analysis are described
Isotopic and spin selectivity of H_2 adsorbed in bundles of carbon nanotubes
Due to its large surface area and strongly attractive potential, a bundle of
carbon nanotubes is an ideal substrate material for gas storage. In addition,
adsorption in nanotubes can be exploited in order to separate the components of
a mixture. In this paper, we investigate the preferential adsorption of D_2
versus H_2(isotope selectivity) and of ortho versus para(spin selectivity)
molecules confined in the one-dimensional grooves and interstitial channels of
carbon nanotube bundles. We perform selectivity calculations in the low
coverage regime, neglecting interactions between adsorbate molecules. We find
substantial spin selectivity for a range of temperatures up to 100 K, and even
greater isotope selectivity for an extended range of temperatures,up to 300 K.
This isotope selectivity is consistent with recent experimental data, which
exhibit a large difference between the isosteric heats of D_2 and H_2 adsorbed
in these bundles.Comment: Paper submitted to Phys.Rev. B; 17 pages, 2 tables, 6 figure
Dried small fish provide nutrient densities important for the first 1000 days
Open Access Journal; Published online: 04 May 2021Inadequate nutrient intakes are prevalent among many populations in sub-Saharan Africa and increasing fish consumption among pregnant/lactating women and children is one strategy to improve diets and address nutrient deficiencies. We report the nutrient content of two fish-based recipesâfish powder and fish chutneyâthat contain dried small fish available in local markets in Zambia. The contribution of a serving of each recipe to the recommended daily intakes of iron, zinc, calcium and docosahexaenoic acid (DHA) for pregnant/lactating women and children 6â24âmonths was calculated because these nutrients are commonly deficient in African diets. We found that one 10-g serving of fish powder provides 20% or more of the daily calcium recommendation and 37% or more of the daily DHA recommendation for both pregnant/lactating women and children. A 30-g serving of fish chutney provides over 40% of the daily calcium recommendation for pregnant women and over 50% for lactating women. Additionally, we investigated the nutrient density (nutrients per kilocalorie) of the fish powder and compared it with the nutrient density of a small-quantity lipid-based nutrient supplement plus (SQ-LNS-plus). SQ-LNS-plus is designed to enhance children's diets by providing micronutrients and DHA. Fish powder is similar to SQ-LNS-plus in iron and zinc density and even higher in calcium and DHA density. Consuming dried small fish as part of a daily meal can be a viable strategy for combatting nutrient deficiencies in the first 1000âdays
Regulation of haemopoietic stemâcell proliferation in mice carrying the Slj allele
We investigated a haemopoietic stromal defect, in mice heterozygous for the Slj allele, during haemopoietic stress induced by treatment with bacterial lipopolysaccharides (LPS) or lethal total body irradiation (TBI) and boneâmarrow cell (BMC) reconstitution. Both treatments resulted in a comparable haemopoietic stem cell (CFUâs) proliferation in Slj/+ and +/+ haemopoietic organs. There was no difference in committed haemopoietic progenitor cell (BFUâe and CFUâG/M) kinetics after TBI and +/+ boneâmarrow transplantation in Slj/+ and +/+ mice. the Slj/+ mice were deficient in their ability to support macroscopic spleen colony formation (65% of +/+ controls) as measured at 7 and 10 days after BMC transplantation. However, the Slj/+ spleen colonies contained the same number of BFUâE and CFUâG/M as colonies from +/+ spleens, while their CFUâs content was increased. On day 10 postâtransplantation, the macroscopic âmissingâ colonies could be detected at the microscopic level. These small colonies contained far fewer CFUâs than the macroscopic detectable colonies. Analysis of CFUâs proliferationâinducing activities in control and postâLPS sera revealed that Slj/+ mice are normal in their ability to produce and to respond to humoral stemâcell regulators. We postulate that Slj/+ mice have a normal number of splenic stromal ânichesâ for colony formation. However, 35% of these niches is defective in its proliferative support. Copyrigh
Uptake of gases in bundles of carbon nanotubes
Model calculations are presented which predict whether or not an arbitrary
gas experiences significant absorption within carbon nanotubes and/or bundles
of nanotubes. The potentials used in these calculations assume a conventional
form, based on a sum of two-body interactions with individual carbon atoms; the
latter employ energy and distance parameters which are derived from empirical
combining rules. The results confirm intuitive expectation that small atoms and
molecules are absorbed within both the interstitial channels and the tubes,
while large atoms and molecules are absorbed almost exclusively within the
tubes.Comment: 9 pages, 12 figures, submitted to PRB Newer version (8MAR2K). There
was an error in the old one (23JAN2K). Please download thi
Classtalk: A Classroom Communication System for Active Learning
This pdf file is an article describing the advantages of using Classtalk technology in the classroom to enhance classroom communication. Classtalk technology cab facilitate the presentation of questions for small group work, collec the student answers and then display histograms showing how the class answered. This new communication technology can help instructors create a more interactive, student centered classroom, especially when teaching large courses. The article describes Classtalk as a very useful tool not only for engaging students in active learning, but also for enhancing the overall communication within the classroom. This article is a selection from the electronic Journal for Computing in Higher Education. Educational levels: Graduate or professional
Hamiltonian dynamics and Noether symmetries in Extended Gravity Cosmology
We discuss the Hamiltonian dynamics for cosmologies coming from Extended
Theories of Gravity. In particular, minisuperspace models are taken into
account searching for Noether symmetries. The existence of conserved quantities
gives selection rule to recover classical behaviors in cosmic evolution
according to the so called Hartle criterion, that allows to select correlated
regions in the configuration space of dynamical variables. We show that such a
statement works for general classes of Extended Theories of Gravity and is
conformally preserved. Furthermore, the presence of Noether symmetries allows a
straightforward classification of singularities that represent the points where
the symmetry is broken. Examples of nonminimally coupled and higher-order
models are discussed.Comment: 20 pages, Review paper to appear in EPJ
Arsenic-gene interactions and beta-cell function in the Strong Heart Family Study
We explored arsenic-gene interactions influencing pancreatic beta-cell activity in the Strong Heart Family Study (SHFS). We considered 42 variants selected for associations with either beta-cell function (31 variants) or arsenic metabolism (11 variants) in the SHFS. Beta-cell function was calculated as homeostatic model - beta corrected for insulin resistance (cHOMA-B) by regressing homeostatic model â insulin resistance (HOMA-IR) on HOMA-B and adding mean HOMA-B. Arsenic exposure was dichotomized at the median of the sum of creatinine-corrected inorganic and organic arsenic species measured by high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICPMS). Additive GxE models for cHOMA-B were adjusted for age and ancestry, and accounted for family relationships. Models were stratified by center (Arizona, Oklahoma, North Dakota and South Dakota) and meta-analyzed. The two interactions between higher vs. lower arsenic and SNPs for cHOMA-B that were nominally significant at P < 0.05 were with rs10738708 (SNP overall effect â3.91, P = 0.56; interaction effect with arsenic â31.14, P = 0.02) and rs4607517 (SNP overall effect +16.61, P = 0.03; interaction effect with arsenic +27.02, P = 0.03). The corresponding genes GCK and TUSC1 suggest oxidative stress and apoptosis as possible mechanisms for arsenic impacts on beta-cell function. No interactions were Bonferroni-significant (1.16 Ă 10â3). Our findings are suggestive of oligogenic moderation of arsenic impacts on pancreatic ÎČ-cell endocrine function, but were not Bonferroni-significant
Differential cross section and recoil polarization measurements for the gamma p to K+ Lambda reaction using CLAS at Jefferson Lab
We present measurements of the differential cross section and Lambda recoil
polarization for the gamma p to K+ Lambda reaction made using the CLAS detector
at Jefferson Lab. These measurements cover the center-of-mass energy range from
1.62 to 2.84 GeV and a wide range of center-of-mass K+ production angles.
Independent analyses were performed using the K+ p pi- and K+ p (missing pi -)
final-state topologies; results from these analyses were found to exhibit good
agreement. These differential cross section measurements show excellent
agreement with previous CLAS and LEPS results and offer increased precision and
a 300 MeV increase in energy coverage. The recoil polarization data agree well
with previous results and offer a large increase in precision and a 500 MeV
extension in energy range. The increased center-of-mass energy range that these
data represent will allow for independent study of non-resonant K+ Lambda
photoproduction mechanisms at all production angles.Comment: 22 pages, 16 figure
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