1,615 research outputs found
Centrifuge rolling test for ore liquefaction analysis
To study the development of liquefaction in ore cargo, a new Rolling Test has been designed to support similar stresses than those observed in a vessel. It can be used in an 80Ăg macrogravity field in the 5.5m radius Ifsttar geo-centrifuge. Its main characteristics are presented
Microlever with combined integrated sensor/actuator functions for scanning force microscopy
A novel silicon microfabricated sensor head for the scanning force microscope (SFM) is presented. The force sensor consists of a cantilever and an adjacent counter-electrode forming the two plates of a capacitor. Force-induced cantilever deflections are monitored by capacitive detection. Typical lever dimensions of 800 um x 40 um and a gap of 3 um yield an active sensing capacitance C=O.l pF. The expected sensitivity in terms of vertical cantilever motion is dC/dz=10 fF/m. In addition to the sensing capability, the microlever can also be z-actuated by applying controlled voltages. This allows both the tip-to-sample distance and the cantilever/system compliance to be adjusted. Expressions are derived for the amplitude of cantilever deflections under electrostatic actuation in the static and dynamic modes as pertinent to applications of SFM in the contact and non-contact modes. The microlever is fabricated using silicon bulk- and surface-micromachining techniques including fusion bonding and sacrificial layer etching. First measurements of the static and dynamic deflections of cantilevers are analysed and show promising results. The reported device basically represents a module of an SFM microsystem with integrated cantilever deflection sensor and adjustment capability
Microlever with combined integrated sensor/actuator functions for scanning force microscopy
A novel silicon microfabricated sensor head for the scanning force microscope (SFM) is presented. The force sensor consists of a cantilever and an adjacent counter-electrode forming the two plates of a capacitor. Force-induced cantilever deflections are monitored by capacitive detection. Typical lever dimensions of 800 um x 40 um and a gap of 3 um yield an active sensing capacitance C=O.l pF. The expected sensitivity in terms of vertical cantilever motion is dC/dz=10 fF/m. In addition to the sensing capability, the microlever can also be z-actuated by applying controlled voltages. This allows both the tip-to-sample distance and the cantilever/system compliance to be adjusted. Expressions are derived for the amplitude of cantilever deflections under electrostatic actuation in the static and dynamic modes as pertinent to applications of SFM in the contact and non-contact modes. The microlever is fabricated using silicon bulk- and surface-micromachining techniques including fusion bonding and sacrificial layer etching. First measurements of the static and dynamic deflections of cantilevers are analysed and show promising results. The reported device basically represents a module of an SFM microsystem with integrated cantilever deflection sensor and adjustment capability
High-Velocity Features: a ubiquitous property of Type Ia SNe
Evidence of high-velocity features such as those seen in the near-maximum
spectra of some Type Ia Supernovae (eg SN 2000cx) has been searched for in the
available SNIa spectra observed earlier than one week before B maximum. Recent
observational efforts have doubled the number of SNeIa with very early spectra.
Remarkably, all SNeIa with early data (7 in our RTN sample and 10 from other
programmes) show signs of such features, to a greater or lesser degree, in CaII
IR, and some also in SiII 6255A line. High-velocity features may be interpreted
as abundance or density enhancements. Abundance enhancements would imply an
outer region dominated by Si and Ca. Density enhancements may result from the
sweeping up of circumstellar material by the highest velocity SN ejecta. In
this scenario, the high incidence of HVFs suggests that a thick disc and/or a
high-density companion wind surrounds the exploding white dwarf, as may be the
case in Single Degenerate systems. Large-scale angular fluctuations in the
radial density and abundance distribution may also be responsible: this could
originate in the explosion, and would suggest a deflagration as the more likely
explosion mechanism. CSM-interaction and surface fluctuations may coexist,
possibly leaving different signatures on the spectrum. In some SNe the HVFs are
narrowly confined in velocity, suggesting the ejection of blobs of burned
material.Comment: 12 pages, 2 figures, ApJ Letters in pres
The genome and transcriptome of Trichormus sp NMC-1: insights into adaptation to extreme environments on the Qinghai-Tibet Plateau
The Qinghai-Tibet Plateau (QTP) has the highest biodiversity for an extreme environment worldwide, and provides an ideal natural laboratory to study adaptive evolution. In this study, we generated a draft genome sequence of cyanobacteria Trichormus sp. NMC-1 in the QTP and performed whole transcriptome sequencing under low temperature to investigate the genetic mechanism by which T. sp. NMC-1 adapted to the specific environment. Its genome sequence was 5.9 Mb with a G+C content of 39.2% and encompassed a total of 5362 CDS. A phylogenomic tree indicated that this strain belongs to the Trichormus and Anabaena cluster. Genome comparison between T. sp. NMC-1 and six relatives showed that functionally unknown genes occupied a much higher proportion (28.12%) of the T. sp. NMC-1 genome. In addition, functions of specific, significant positively selected, expanded orthogroups, and differentially expressed genes involved in signal transduction, cell wall/membrane biogenesis, secondary metabolite biosynthesis, and energy production and conversion were analyzed to elucidate specific adaptation traits. Further analyses showed that the CheY-like genes, extracellular polysaccharide and mycosporine-like amino acids might play major roles in adaptation to harsh environments. Our findings indicate that sophisticated genetic mechanisms are involved in cyanobacterial adaptation to the extreme environment of the QTP
Background Light in Potential Sites for the ANTARES Undersea Neutrino Telescope
The ANTARES collaboration has performed a series of {\em in situ}
measurements to study the background light for a planned undersea neutrino
telescope. Such background can be caused by K decays or by biological
activity. We report on measurements at two sites in the Mediterranean Sea at
depths of 2400~m and 2700~m, respectively. Three photomultiplier tubes were
used to measure single counting rates and coincidence rates for pairs of tubes
at various distances. The background rate is seen to consist of three
components: a constant rate due to K decays, a continuum rate that
varies on a time scale of several hours simultaneously over distances up to at
least 40~m, and random bursts a few seconds long that are only correlated in
time over distances of the order of a meter. A trigger requiring coincidences
between nearby photomultiplier tubes should reduce the trigger rate for a
neutrino telescope to a manageable level with only a small loss in efficiency.Comment: 18 pages, 8 figures, accepted for publication in Astroparticle
Physic
Patterning in Birthweight in India: Analysis of Maternal Recall and Health Card Data
National data on birthweight from birth certificates or medical records are not available in India. The third Indian National Family Health Survey included data on birthweight of children obtained from health cards and maternal recall. This study aims to describe the population that these data represent and compares the birthweight obtained from health cards with maternal recall data in terms of its socioeconomic patterning and as a risk factor for childhood growth failure.The analytic sample consisted of children aged 0 to 59 months with birthweight data obtained from health cards (n = 3227) and maternal recall (n = 16,787). The difference between the card sample and the maternal recall sample in the distribution across household wealth, parental education, caste, religion, gender, and urban residence was compared using multilevel models. We also assessed the ability of birthweight to predict growth failure in infancy and childhood in the two groups. The survey contains birthweight data from a majority of household wealth categories (>5% in every category for recall), both genders, all age groups, all caste groups, all religion groups, and urban and rural dwellers. However, children from the lowest quintile of household wealth were under-represented (4.73% in card and 8.62% in recall samples). Comparison of data across health cards and maternal recall revealed similar social patterning of low birthweight and ability of birthweight to predict growth failure later in life. Children were less likely to be born with low birthweight if they had mothers with over 12 years of education compared to 1-5 years of education with relative risk (RR) of 0.79 (95% confidence interval [CI]: 0.52, 1.2) in the card sample and 0.70 (95% CI: 0.59, 0.84) in the recall sample. A 100 gram difference in a child's birthweight was associated with a decreased likelihood of underweight in both the card (RR: 0.95; 95% CI: 0.94, 0.96) and recall (RR: 0.96; 95% CI: 0.96, 0.97) samples.Our results suggest that in the absence of other sources, the data on birthweight in the third Indian National Family Health Survey is valuable for epidemiologic research
Differential branching fraction and angular analysis of the decay B0âKâ0ÎŒ+ÎŒâ
The angular distribution and differential branching fraction of the decay B 0â K â0 ÎŒ + ÎŒ â are studied using a data sample, collected by the LHCb experiment in pp collisions at sâ=7 TeV, corresponding to an integrated luminosity of 1.0 fbâ1. Several angular observables are measured in bins of the dimuon invariant mass squared, q 2. A first measurement of the zero-crossing point of the forward-backward asymmetry of the dimuon system is also presented. The zero-crossing point is measured to be q20=4.9±0.9GeV2/c4 , where the uncertainty is the sum of statistical and systematic uncertainties. The results are consistent with the Standard Model predictions
Opposite-side flavour tagging of B mesons at the LHCb experiment
The calibration and performance of the oppositeside
flavour tagging algorithms used for the measurements
of time-dependent asymmetries at the LHCb experiment
are described. The algorithms have been developed using
simulated events and optimized and calibrated with
B
+ âJ/ÏK
+, B0 âJ/ÏK
â0 and B0 âD
ââ
Ό
+
ΜΌ decay
modes with 0.37 fbâ1 of data collected in pp collisions
at
â
s = 7 TeV during the 2011 physics run. The oppositeside
tagging power is determined in the B
+ â J/ÏK
+
channel to be (2.10 ± 0.08 ± 0.24) %, where the first uncertainty
is statistical and the second is systematic
- âŠ