Evaluating Cache Coherent Shared Virtual Memory for Heterogeneous Multicore Chips

The trend in industry is towards heterogeneous multicore processors (HMCs), including chips with CPUs and massively-threaded throughput-oriented processors (MTTOPs) such as GPUs. Although current homogeneous chips tightly couple the cores with cache-coherent shared virtual memory (CCSVM), this is not the communication paradigm used by any current HMC. In this paper, we present a CCSVM design for a CPU/MTTOP chip, as well as an extension of the pthreads programming model, called xthreads, for programming this HMC. Our goal is to evaluate the potential performance benefits of tightly coupling heterogeneous cores with CCSVM

Molecular Identification of Eimeria Species in Broiler Chickens in Trinidad, West Indies

Coccidiosis is an intestinal disease of chickens of major economic importance to broiler industries worldwide. Species of coccidia found in chickens include Eimeria acervulina, Eimeria brunetti, Eimeria maxima, Eimeria mitis, Eimeria necatrix, Eimeria praecox, and Eimeria tenella. In recent years, polymerase chain reaction (PCR) has been developed to provide accurate and rapid identification of the seven known Eimeria species of chickens. The aim of this study was to use species-specific real-time PCR (qPCR) to identify which of the seven Eimeria species are present in Trinidad poultry. Seventeen pooled fecal samples were collected from 6 broiler farms (2–5 pens per farm) across Trinidad. Feces were also collected from birds showing clinical signs of coccidiosis in two live bird markets (pluck shops). qPCR revealed the presence of five species of Eimeria (E. acervulina, E. maxima, E. mitis, E. necatrix, and E. tenella), but not E. brunetti or E. praecox. Mixed infections were detected on all broiler farms, and DNA of two highly pathogenic Eimeria species (E. tenella and E. necatrix) was detected in feces taken from clinically sick birds sampled from the two pluck shops

Fluid mechanics of nodal flow due to embryonic primary cilia

Breaking of left–right symmetry is crucial in vertebrate development. The role of cilia-driven flow has been the subject of many recent publications, but the underlying mechanisms remain controversial. At approximately 8 days post-fertilization, after the establishment of the dorsal–ventral and anterior–posterior axes, a depressed structure is found on the ventral side of mouse embryos, termed the ventral node. Within the node, ‘whirling’ primary cilia, tilted towards the posterior, drive a flow implicated in the initial left–right signalling asymmetry. However, the underlying fluid mechanics have not been fully and correctly explained until recently and accurate characterization is required in determining how the flow triggers the downstream signalling cascades. Using the approximation of resistive force theory, we show how the flow is produced and calculate the optimal configuration to cause maximum flow, showing excellent agreement with in vitro measurements and numerical simulation, and paralleling recent analogue experiments. By calculating numerical solutions of the slender body theory equations, we present time-dependent physically based fluid dynamics simulations of particle pathlines in flows generated by large arrays of beating cilia, showing the far-field radial streamlines predicted by the theory

Mathematical modelling of cilia driven transport of biological fluids

Cilia-driven flow occurs in the airway surface liquid, in the female and male reproductive tracts and enables symmetry-breaking in the embryonic node. Viscoelastic rheology is found in healthy states in some systems, whereas in others may characterise disease, motivating the development of mathematical models that take this effect into account. We derive the fundamental solution for linear viscoelastic flow, which is subsequently used as a basis for slender-body theory. Our numerical algorithm allows efficient computation of three-dimensional time-dependent flow, bending moments, power and particle transport. We apply the model to the large-amplitude motion of a single cilium in a linear Maxwell liquid. A relatively short relaxation time of just 0.032 times the beat period significantly reduces forces, bending moments, power and particle transport, the last variable exhibiting exponential decay with relaxation time. A test particle is propelled approximately one-fifth as quickly along the direction of cilia beating for scaled relaxation time 0.032 as in the Newtonian case, and mean volume flow is abolished, emphasizing the sensitivity of cilia function to fluid rheology. These results may have implications for flow in the airways, where the transition from Newtonian to viscoelastic rheology in the peri-ciliary fluid may reduce clearance

Reduction and analysis of ATS-6 data

Results obtained from the analysis of data returned by the energetic particle spectrometer on ATS 6 are presented. The study of the energetic electron environment and the effects of the solar wind parameters on the energetic electrons trapped at the synchronous altitude are emphasized

Reduction and analysis of ATS-6 data

A data reduction program was developed and debugged which presents the Aerospace particle data and the UCLA magnetometer data in a variety of formats suitable for analysis as well as further data processing. Fifty days of data were processed through this program and analysis of these data were begun. In addition, modifications were made to an old ATS-1 program in order to enable this program to process ATS-1 data obtained simultaneously with ATS-6 data acquisitions during 1974. Some analysis of ATS-1 data and comparison with ATS-6 data also went forward. Preparations were begun to transfer ATS-6 data to the National Space Science Data Center. These efforts are described in detail

Observations of Rotationally Resolved C_3 in Translucent Sight Lines

The rotationally resolved spectrum of the A^1Π_u ← X^1Σ^+_g 000-000 transition of C_3, centered at 4051.6 Å, has been observed along 10 translucent lines of sight. To interpret these spectra, a new method for the determination of column densities and analysis of excitation profiles involving the simulation and fitting of observed spectra has been developed. The populations of lower rotational levels (J ≤ 14) in C_3 are best fitted by thermal distributions that are consistent with the kinetic temperatures determined from the excitation profile of C_2. Just as in the case of C_2, higher rotational levels (J > 14) of C_3 show increased nonthermal population distributions in clouds that have been determined to have total gas densities below ~500 cm^(-3)

The Faint Young Sun Paradox: An Observational Test of an Alternative Solar Model

We report the results of deep observations at radio (3.6 cm) wavelengths of the nearby solar‐type star π^01 Ursa Majoris with the Very Large Array (VLA) intended to test an alternative theory of solar luminosity evolution. The standard model predicts a solar luminosity only 75% of the present value and surface temperatures below freezing on Earth and Mars at 4 Ga, seemingly in conflict with geologic evidence for liquid water on these planets. An alternative model invokes a compensatory mass loss through a declining solar wind that results in a more consistent early luminosity. The free‐free emission from an enhanced wind around nearby young Sun‐like stars should be detectable at microwave frequencies. Our observations of π^01 UMa, a 300 million year‐old solar‐mass star, place an upper limit on the mass loss rate of 4–5 × 10^(−11) M_⊙ yr^(−1). Total mass loss from such a star over 4 Gyr would be less than 6%. If this star is indeed an analog of the early Sun, it casts doubt on the alternative model as a solution to the faint young Sun paradox, particularly for Mars

Diffuse Interstellar Bands Toward HD 62542

Diffuse interstellar bands (DIBs) have been detected for the first time along the peculiar translucent line of sight toward HD 62542, which passes through a diffuse cloud core. Although only a small fraction (18 out of more than 300) of generally weak DIB features have been shown to correlate with C_2 and C_3 (the "C_2 DIBs"), it is predominantly these DIBs that are observed toward HD 62542. The typically strong DIBs λλ5780 and 5797 are detected but are significantly weaker than toward other lines of sight with similar reddening. Other commonly observed DIBs (such as λλ4430, 6270, and 6284) remain noticeably absent. These observations further support the suggestion that the line of sight toward HD 62542 crosses only the core of a diffuse cloud and show that the correlation between the C_2 DIBs and small carbon chains is maintained in environments with very large fractions of molecular hydrogen, f_(H_2) > 0.8. A comparison of CH, CN, C_2, and C_3 column densities and C_2 DIB strengths toward HD 62542, HD 204827, and HD 172028 suggests that the line of sight toward HD 204827 passes through a diffuse cloud core similar to that seen toward HD 62542, as well as what might be referred to as a diffuse cloud envelope. This indicates that the bare core toward HD 62542 may not have significantly different relative chemical abundances from other diffuse cloud cores and that the C_2 DIBs may serve as a diagnostic of such cores

HCl Absorption Toward Sagittarius B2

We have detected the 626 GHz J = 1 → 0 transition of hydrogen chloride (H^(35)Cl) in absorption against the dust continuum emission of the molecular cloud Sagittarius B2. The observed line shape is consistent with the blending of the three hyperfine components of this transition by the velocity profile of Sgr B2 observed in other species. The apparent optical depth of the line is t ≈ 1, and the minimum HCl column density is 1.6 x 10^(14) cm^(-2) A detailed radiative transfer model was constructed which includes collisional and radiative excitation, absorption and emission by dust, and the radial variation of temperature and density. Good agreement between the model and the data is obtained for HCl/H_2 ~ 1.1 x 10^(-9). Comparison of this result to chemical models indicates that the depletion factor of gas-phase chlorine is between 50–180 in the molecular envelope surrounding the SgrB2(N) and (M) dust cores