Nominal Core Research Articles

BH3 domain-independent apolipoprotein L1 toxicity rescued by BCL2 prosurvival proteins

The potent trypanolytic properties of human apolipoprotein L1 (APOL1) can be neutralized by the trypanosome variant surface antigen gene product known as serum resistance-associated protein. However, two common APOL1 haplotypes present uniquely in individuals of West African ancestry each encode APOL1 variants resistant to serum resistance-associated protein, and each confers substantial resistance to human African sleeping sickness. In contrast to the dominantly inherited anti-trypanosomal activity of APOL1, recessive inheritance of these two trypanoprotective APOL1 alleles predisposes to kidney disease. Proposed mechanisms of APOL1 toxicity have included BH3 domain-dependent autophagy and/or ion channel activity. We probed these potential mechanisms by expressing APOL1 in Xenopus laevis oocytes. APOL1 expression in oocytes increased ion permeability and caused profound morphological deterioration (toxicity). Coexpression of BCL2 family members rescued APOL1-associated oocyte toxicity in the order MCL1 ∼ BCLW > BCLXL ∼ BCL2A1 ≫ BCL2. Deletion of nine nominal core BH3 domain residues abolished APOL1-associated toxicity, but missense substitution of the same residues abolished neither oocyte toxicity nor its rescue by coexpressed MCL1. The APOL1 BH3 domain was similarly dispensable for the ability of APOL1 to rescue intact mice from lethal trypanosome challenge. Replacement of most extracellular Na(+) by K(+) also reduced APOL1-associated oocyte toxicity, allowing demonstration of APOL1-associated increases in Ca(2+) and Cl(-) fluxes and oocyte ion currents, which were similarly reduced by MCL1 coexpression. Thus APOL1 toxicity in Xenopus oocytes is BH3-independent, but can nonetheless be rescued by some BCL2 family proteins.

STABILITY AND COALESCENCE OF MASSIVE TWIN BINARIES

Massive stars are usually found in binaries, and binaries with periods less than 10 days may have a preference for near equal component masses. In this paper we investigate the evolution of these binaries all the way to contact and the possibility that these systems can be progenitors of double neutron star binaries. The small orbital separations of observed double neutron star binaries suggest that the progenitor systems underwent a common envelope phase at least once during their evolution. Bethe & Brown (1998) proposed that massive binary twins will undergo a common envelope evolution while both components are ascending the red giant branch or asymptotic giant branch simultaneously, also known as double-core evolution. Using models generated from the stellar evolution code Evolve Zero Age Main Sequence, we determine the range of mass ratios resulting in both components simultaneously ascending the RGB or AGB as a function of the difference in birth times, t. We find that, even for a generous t=5 Myr, the minimum mass ratio qmin=0.933 for an 8 Solar Mass primary and increases for larger primaries. We use a hydrodynamics code, StarSmasher, to study specifically the evolution of q=1 common envelope systems as a function of initial component mass, age, and orbital separation. We find the dynamical stability limit, the largest orbital separation where the binary becomes dynamically unstable, as a function of the component mass and age. Finally, we calculate the efficiency of ejecting matter during the inspiral phase to extrapolate the properties of the remnant binary from our numerical results, assuming the common envelope is completely ejected. We find that for the nominal core masses, there is a minimum orbital separation for a given component mass such that the helium cores survive common envelope evolution in a tightly bound binary and are viable progenitors for double neutron stars.

Suitability of magnetic single- and multi-core nanoparticles to detect protein binding with dynamic magnetic measurement techniques

We investigated the binding of biotinylated proteins to various streptavidin functionalized magnetic nanoparticles with different dynamic magnetic measurement techniques to examine their potential for homogeneous bioassays. As particle systems, single-core nanoparticles with a nominal core diameter of 30 nm as well as multi-core nanoparticles with hydrodynamic sizes varying between nominally 60 nm and 100 nm were chosen. As experimental techniques, fluxgate magnetorelaxometry (MRX), complex ac susceptibility (ACS) and measurements of the phase lag between rotating field and sample magnetization are applied. MRX measurements are only suited for the detection of small analytes if the multivalency of functionalized nanoparticles and analytes causes cross-linking, thus forming larger aggregates. ACS measurements showed for all nanoparticle systems a shift of the imaginary part's maximum towards small frequencies. In rotating field measurements only the single-core nanoparticle systems with dominating Brownian mechanism exhibit an increase of the phase lag upon binding in the investigated frequency range. The coexistence of Brownian and Neel relaxation processes can cause a more complex phase lag change behavior, as demonstrated for multi-core nanoparticle systems.

All-Digital Simple Clock Synthesis Through a Glitch-Free Variable-Length Ring Oscillator

This brief presents a simple all-digital variable-length ring oscillator (VLRO) design that is capable of synchronously changing the output frequency while keeping a signal free of glitches or spurious oscillations at the frequency transitions. The correct operation of the proposed VLRO has been experimentally validated on a 90-nm Xilinx Spartan-3E field-programmable gate array, showing the ability to switch between 16 different frequencies (from 24.1 to 321 MHz for the nominal core supply voltage) under different supply voltages with the expected behavior.

ANTINEUTRINOS FOR REACTOR SAFEGUARDS: EFFECT OF FUEL LOADING AND BURNUP ON THE SIGNAL

Various types of nuclear reactor related information, including relative power level and fuel evolution parameters, can be inferred remotely using antineutrino detectors. We show that it is possible to verify assembly-level burnup using information derived from an antineutrino detector if the nominal reactor fuel loading is known. Alternatively, if the core power is measured using an independent method, for example, a thermal hydraulic element, and the nominal core behavior is known, the antineutrino detector has a capability to determine previously unknown MOX loading in the core.

Microfluidic Platform for Magnetic Nanoparticle Trapping and Detection

We evaluate giant magnetoresistance sensors to trap and count small concentrations of magnetic nanoparticles (MNPs) within microfluidic flow. The device presented takes the novel approach of capturing and detecting MNPs utilizing the strong fringe-fields present on the periphery of the patterned sensor. The presence of MNPs manifests as a field shift in the magnetoresistance curve. Tests of the device have shown a noticeable response to MNPs with 30 nm nominal core diameters at concentrations as low as <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$1.2\times 10^{10}\pm 4.0\times 10^{9}\ {\rm MNP/mL}$</tex> </formula> at a flow rate of 5 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu{\rm L/min}$</tex></formula> . Such a device would be beneficial for bio-medical applications, including immunoassays, and for monitoring filtration processes, where large sample fluid volumes and low MNP concentration sensitivities are required.

The temporal evolution of the July 2009 Jupiter impact cloud

Clouds formed on Jupiter by the impact of July 19, 2009 were observed from the IRTF with the same instrument and near-infrared filters during four observing runs over 50 days, beginning one day after impact, providing comprehensive diagnostics of cloudtop altitude, particle size and opacity and yielding quantitative information on the temporal evolution of the impact cloud (IC). The IC evolved relatively rapidly during the first 26 days after impact (Period I) and relatively slowly for the next 23 days (Period II). For the column volume density of the IC core, analyzed over a range of models with varying Mie-scattering particle radii over 0.1–1.1μm and imaginary indices of refraction (ni) from 0.001 to the limiting model-constrained value of 0.03, the Period I e-folding timescale is 4–16 times less than for Period II, with a best-fit timescale of of 23 days (Period I) increasing to 117 days (Period II) for the nominal best-fit case of large (0.7–1.1μm) dark (ni=0.01) particles consistent with previous determinations of the size and near-infrared brightness of impact cloud particles (de Pater et al. Icarus 210, 722–741, 2010). Over the entire period, the nominal model mean particle radius ranges from ∼0.85μm one day after impact to 0.89–1.06μm 49 days later, considerably larger than the 0.21–0.28μm particles determined for the Shoemaker Levy 9 impact (SL9; West et al., Science 267, 1296–1301, 1995). The 1.69 and 2.12μm nominal model IC core opacities show timescales averaged over the entire seven-week period of ∼33 and ∼35 days, respectively, ∼60% longer than the 18–23 day timescales of small-particle models (∼0.36μm radius) which are more consistent with the ∼15-day visible timescale reported by Sánchez-Lavega et al. (2011, Icarus 214,462–476). Including the area of the entire IC, we find that the total particle volume over the 49 days changes from ∼0.036 to ∼0.022km3 for the nominal model, corresponding to a variation of the diameter of an equivalent sphere from ∼0.41 to ∼0.35km, close to the ∼10% diameter change over one month reported for SL9 clouds (West et al, ibid). Nominal Period II timescales for opacities and total cloud volume – 50–300 days – are 2–11 times longer than nominal Period I timescales; indeed, values of infinity are consistent with the uncertainties. The relatively long timescales found for total cloud dissipation are consistent with (1) material dispersal by wind shears, and (2) relatively weak sedimentation/coagulation, consistent with SL9 results (West et al., ibid). Finally, the IC thickness of ∼1 scale-height permits a vertical windshear of ∼1m/s, inconsistent with the derived ∼7m/s cloud spreading, thus implying that the meridional shear is the dominant cloud shear component, as reported for visible measurements (Sánchez-Lavega et al. ibid).

Three-dimensional elemental mapping of hollow Fe2O3@SiO2 mesoporous spheres using scanning confocal electron microscopy

Energy filtered scanning confocal electron microscopy (EFSCEM) in an aberration-corrected transmission electron microscope offers an approach for three-dimensional imaging and chemical analysis of nanoscale materials related to the well-established technique of confocal scanning optical microscopy. Here, we apply EFSCEM to the compositional analysis of the core structure in candidate structures for targeted drug delivery. Element-specific optical sectioning along the specimen depth direction demonstrates the presence of additional Si in a nominal Fe2O3 core. The presence of Si in the core is consistent with a specific formation mechanism for the hollow structure of the core.

Approach to equilibrium fuelling scheme of 500 MWe PFBR based on 3-D core burnup modeling

Approach to equilibrium fuelling scheme of 500 MWe prototype fast breeder reactor (PFBR) has been predicted using detailed 3-D core burnup modeling. Equilibrium is reached after two cycles of 180 effective full power days (efpd) each. One-third core is refueled every time in a repeatable scatter load scheme after every 3 cycles. Considering the constraints of linear heat rating (LHR) on fuel and blanket pins it is found that the nominal core achieves full power only in mid-cycle. A novel interpolation scheme is used to find the peak LHR in any axial section of a fuel/blanket sub-assembly. Breeding ratio is adequate for self-sufficient Pu generation in a closed fuel cycle with Pu from axial blankets and two rings of radial blanket sub-assemblies.

A thermochemical boundary layer at the base of Earth's outer core and independent estimate of core heat flux

SUMMARY Recent seismological observations suggest the existence of a ≈150-km-thick density-stratified layer with a P-wave velocity gradient that differs slightly from PREM. Such a structure can only be caused by a compositional gradient, effects of a slurry or temperature being too small and probably the wrong sign. We propose a stably stratified, variable concentration layer on the liquidus. Heat is transported by conduction down the liquidus while the light and heavy components migrate through the layer by a process akin to zone refining, similar to the one originally proposed by Braginsky. The layer remains static in a frame of reference moving upwards with the expanding inner core boundary. We determine the gradient using estimates of co, the concentration in the main body of the outer core, and cb, the concentration of the liquid at the inner core boundary. We determine the depression of the melting point and concentrations using ideal solution theory and seismologically determined density jumps at the inner core boundary. We suppose that co determines �ρ mod, the jump from normal mode eigenfrequencies that have long resolution lengths straddling the entire layer, and that cb determines �ρ bod, the jump determined from body waves, which have fine resolution. A simple calculation then yields the seismic, temperature, and concentration profiles within the layer. Comparison with the distance to the C-cusp of PKP and normal mode eigenfrequencies constrain the model. We explore a wide range of possible input parameters; many fail to predict sensible seismic properties and heat fluxes. A model with �ρ mod = 0.8 gm cc −1 , �ρ bod = 0.6 gm cc −1 , and layer thickness 200 km is consistent with the seismic observations and can power the geodynamo with a reasonable inner core heat flux of ≈2 TW and nominal inner core age of ≈1 Ga. It is quite remarkable and encouraging that a model based on direct seismic observations and simple chemistry can predict heat fluxes that are comparable with those derived from recent core thermal history calculations. The model also provides plausible explanations of the observed seismic layer and accounts for the discrepancy between estimates of the inner core density jumps derived from body waves and normal modes.

Commissioning of the ATLAS thermal-hydraulic integral test facility

KAERI recently constructed a new thermal-hydraulic integral test facility for advanced pressurized water reactors (PWRs) – ATLAS. The ATLAS facility has the following characteristics: (a) 1/2-height&length, 1/288-volume, and full pressure simulation of APR1400, (b) maintaining a geometrical similarity with APR1400 including 2(hot legs) × 4(cold legs) reactor coolant loops, direct vessel injection (DVI) of emergency core cooling water, integrated annular downcomer, etc., (c) incorporation of specific design characteristics of OPR1000 such as cold leg injection and low-pressure safety injection pumps, (d) maximum 10% of the scaled nominal core power. The ATLAS will mainly be used to simulate various accident and transient scenarios for evolutionary PWRs, OPR1000 and APR1400: the simulation capability of broad scenarios including the reflood phase of a large-break loss-of-coolant accident (LOCA), small-break LOCA scenarios including DVI line breaks, a steam generator tube rupture, a main steam line break, a feed line break, a mid-loop operation, etc. The ATLAS is now in operation after an extensive series of commissioning tests in 2006.

Driving the self assembly of gold nanoparticle structures using highly oriented PTFE templates

We present a non-conventional, low cost and simple approach for patterning gold nanoparticles (NPs) using highly oriented PolyTetraFluoroEthylene (HOPTFE) macromolecular segments on glass substrates. Transparent and stable HOPTFE templates for NP self-assembly were prepared by sliding unidirectionally a PTFE rod across a glass substrate at a fixed temperature with a constant pressure. Gold NPs, 50 nm nominal core diameter stabilized by citrate and octanethiol, have been assembled onto HOPTFE macromolecular segments using two different procedures. The first method is based on the drop casting of octanethiol capped NPs to obtain a growth of 1-D structures onto HOPTFE ridges. The second method exploits the functionalization of the glass substrate using (3-Aminopropyl)-triethatoxysilane (APTES) in order to induce the formation of 2-D structures between HOPTFE ridges. The self organized nanostructures and their morphological features have been investigated using AFM. The core size distribution of gold NPs was analyzed from TEM images.

Development of Operator Action Time for SBLOCA during Plant Shutdown Operation in Power-uprated Kori 3 and 4

The ECCS performance, which mitigates a postulated catastrophic failure of the main reactor coolant piping during the full power operation, is judged to cover the consequences of LOCA occurring in other plant operational states. During Mode 3 with an accumulator isolated and Mode 4, since the normal alignment of ECCS equipments is changed from that which is available during the power operation, a potential safety issue, which involved the performance of ECCS for LOCA during Mode 3 with the accumulator isolated and Mode 4, was identified in 1985. This study is performed as the plant specific shutdown LOCA program for the power uprated Kori-3 and 4, of which the nominal core power is planned to increase by 4.5%. We determine and verify the operator action time to initiate SI following a small break LOCA in order that the peak clad temperature of fuel does not exceed the 10CFR50.46 limit of 1,477.6 K. We evaluate the 0.1524 m (6 inches) pipe break in the cold leg to develop the SI initiation time. There is a considerable margin to the 10CFR50.46 limit of 1,477.6 K in the case that the SI is manually initiated at 25 min after an operator identifies the symptom of a small break LOCA. However, in respect of the safe plant operation, we decide the operator SI initiation time as 15 min in order that the SI water is supplied to prevent the fuel heat-up during the blowdown phase of a small break LOCA. After then, we evaluate the applicability of the pre-determined SI initiation time to other small break LOCAs, which have a smaller break size, a lower initial decay heat level or a different break location. Since the peak clad temperatures of applicability evaluation cases are lower than those of the umbrella case, we confirm that the pre-determined SI initiation time can be applied to mitigate the small break LOCAs during the plant shutdown operation. The SI initiation time developed in this study will be used in the Abnormal Operating Procedure of the power uprated Kori-3 and 4 for the small break LOCAs during the plant shutdown operation.

Die nicht-flektierten Adjektive / The uninflected adjectives

AbstractNon-inflecting adjectives occur not only in predicative, adverbial, co-predicative-adverbial and adadjectival-attributive function, but also occur regularly in adnominal-attributive function in particular types of text. This can occur in both the preposed and postposed position of the governing nominal core of the noun phrase. In contrast, the adnominal-attributive use in the position between the determinative and the governing nominal core is characteristic of inflected adjectives.

Post-fire low velocity impact response of marine grade sandwich composites

Abstract Fire resistance is an important issue in marine grade sandwich structures because core materials tend to degrade rapidly following degradation of the facesheet(s) when exposed to fire. This study investigates the impact behavior of E-glass/vinyl ester (VE) balsa wood core sandwich panels subjected to a 1250 °C, 175 kW m −2 flame for 0, 50, 100, and 200 s. The impact response of fire exposed sandwich panels was evaluated under low velocity impact (LVI) using an instrumented drop tower apparatus. The impact response of the sandwich panels was found to decrease as a function of fire exposure. A loss of stiffness associated with fire exposure was found to change the mechanism of impact energy absorption. A greater nominal wood core density was found to provide more structural integrity and impact resistance as fire exposure increases. In the marine grade sandwich panels tested, the total average ‘peak load’, initial stiffness, and propagation energy impact response characteristics were found to reduce by 73, 81, and 54% following 200 s exposure of a 1250 °C, 175 kW m −2 fire, respectively.

Building neutron cross-section dependencies for few-group reactor calculations using stepwise regression

Approximation of few-group neutron cross-sections by functions of burnup and thermal-hydraulics parameters of a fuel cell is considered. The cross-section is written as a sum of two terms: the base cross-section, which depends only on burnup and is computed under the nominal reactor core conditions, and the deviation, which depends on burnup and thermal-hydraulics variables of the cell. A one-dimensional dependence of the base cross-section is interpolated by a cubic spline. Multi-dimensional dependencies of the deviation are approximated by a polynomial. Construction of the polynomial is performed by a best-fitting selection of the polynomial terms using the stepwise regression algorithm. The number of terms to satisfy a user-given accuracy of approximation is minimized. As an example, approximation of a set of two-group macro and micro cross-sections as functions of burnup, coolant and fuel temperature, coolant density and boron concentration is considered for a fuel pin cell of a VVER reactor. The constructed five-dimensional polynomial approximating cross-sections within 0.05% tolerance has about 20 terms for fast group cross-sections and 50 terms for thermal group cross-sections. The error of approximation is verified on the two data sets: the initial data used for approximation and the test data being computed on randomly selected points. Mean square and maximum errors are comparable for all the cross-sections for both sets of data. These results show that the initial data can be applied to control the approximation error.

Core plasma operation consistent with SOL parameters in ITER

The constraints of divertor operation have been applied to ITER core plasma simulations by imposing boundary conditions on the calculation, implemented as a set of scaling relations derived from B2-Eirene modelling which describe the effect of the divertor. The core plasma simulations use the integrated core pedestal sol (ICPS) model, based on ITG transport for ions and RLW-like transport for electrons, which includes an increase of transport when the ballooning limit is attained in order to simulate the effect of ELMs in a time-averaged fashion. At the nominal average core density for ITER with the ICPS transport model stationary operation with a fusion power multiplier Q of 12–16 is obtained and a reasonable operating range exists for realistic pumping speeds and particle throughput at a peak divertor power load controlled to remain below 10 MW m−2. Fuelling of the plasma must be predominantly direct core fuelling, and the resulting required core-fuelling rates are realistic. Increased pumping speed and particle throughput are beneficial for maximizing Q. The relaxation to these stationary conditions is very slow, and transient values of fusion multiplier are appreciably higher.

Complementary representation and zones of ecological transition

Minimum complementary sets of sites that represent each species at least once have been argued to provide a nominal core reserve network and the starting point for regional conservation programs. However, this approach may be inadequate if there is a tendency to represent several species at marginal areas within their ranges, which may occur if high efficiency results from preferential selection of sites in areas of ecological transition. Here we use data on the distributions of birds in South Africa and Lesotho to explore this idea. We found that for five measures that are expected to reflect the location of areas of ecological transition, complementary sets tend to select higher values of these measures than expected by chance. We recommend that methods for the identification of priority areas for conservation that incorporate viability concerns be preferred to minimum representation sets, even if this results in more costly reserve networks.

10.2172/1062632

This is the second in a series of reports on the response of a BWR/5 boiling water reactor to anticipated transients without reactor scram (ATWS) when operating in the expanded operating domain MELLLA+. In this report ATWS events initiated by a turbine trip are considered at two points in the fuel cycle: beginning of cycle (BOC) and peak excess reactivity (PHE, close to the middle of the cycle). The effect of the gap (between the fuel pellet and clad) conductance modeling, turbine bypass fractions, and initial core flow rates are evaluated.. Two limiting values of gas-gap conductance, the lowest value of 5,000 W/m2-K at BOC and the highest value of 161,000 W/m2-K at PHE, are compared with corresponding base cases which utilized the dynamic gas-gap model. Turbine bypass fractions analyzed are 10% and 25% at PHE and these two sensitivity cases are compared with the 100% bypass base case. The reduced core flow case at 75% of nominal core flow is analyzed at PHE and compared with the base case of 85% core flow. The simulations were carried out using the TRACE/PARCS code system and models developed for a previous study at three different times during a fuel cycle with all relevant BWR/5 systems. The modeling in the core is particularly detailed (four fuel rod types included in each fuel assembly and 382 thermal-hydraulic channels to represent all assemblies taking into account half-core symmetry) in order to capture the complex neutronic-thermal-hydraulic coupling during periods of instability. The study provides insights into reactor behavior during these events, including the impact of assumed operator actions on the oscillatory behavior due to reactor instabilities and on the eventual shutdown of the reactor. It shows the effect of gap conductance, turbine bypass fraction and initial flow rate. and #8195;

Photometrically determined membership of the young, open cluster IC 2391

New 4-colour CCD photometry to a limiting magnitude of is presented for 1428 objects observed towards the direction of the young, open cluster IC 2391. We observed 36 () fields within 17 arcmin of the nominal cluster core. By fitting the theoretical isochrones of D'Antona & Mazzitelli (1994) to a combination of colour-magnitude and colour-colour diagrams, we have identified 17 stars as probable cluster members with a further 85 stars as possible members. The brightness distribution of low-mass members is compared with the luminosity function observed for the Pleiades and we estimate that the contamination due to background giants should be small.