Upstream Arm Research Articles

Simulation of Facet Dendritic Shape of Isothermal Alloy in a Forced Flow by Phase Field Method

Numerical simulation based on a new regularized phase field model was performed to describe the dendritic growth of an isothermal alloy with a strong anisotropy in the presence of a forced flow. These results indicate that a crystal grow into an equiaxial facet dendritic in the absence of a forced flow and into an asymmetrical facet dendritic in the presence of a forced flow. With increasing a flow velocity, the tip steady velocity of upstream dendritic arm increases, that of the downstream arm decreases, and that of the perpendicular arms increases at first, and then decreases, the perpendicular arms gradually grow toward the incoming flow direction. In the certain range of anisotropy parameter, when γ is larger than 0.14, dendritic tip steady velocities in all direction are expected to reach their own saturation values. In addition, the effect of a compound forced flow on an isothermal facet dendritic is similar to experimental results.

Total Spreads Its Wings

Company Profile Series Editor’s note: This is the fourth in a series of profiles of leading operators, including key international and national oil companies, around the globe. The focus is on the company’s strategic direction, relationship to its government, major upstream activity, and significant technology challenges and applications. Integrated French energy giant Total is continuing to spread its wings as it focuses on liquefied natural gas (LNG), deep offshore developments, and heavy oil. The company is seeking to maximize production from its existing fields, while at the same time boosting output from a raft of new projects it is bringing on stream over the next 5 years. Total has ambitious plans to grow oil and gas output by 2% per year and it is trying to strengthen its upstream arm through exploration, partnerships, and targeted asset deals. Total is the fifth-largest publicly traded integrated international oil and gas company in the world and is divided into three business segments—upstream, downstream, and chemicals. It produces oil and gas in more than 30 countries, including Angola, Australia, Nigeria, Algeria, Canada, China, Russia, and Qatar. Production of liquids and natural gas was 2.36 million BOEPD in the second quarter of this year, up 8% from the second quarter 2009, while total 2009 output was 2.28 million BOEPD. The company estimates that the share of gas in production will increase from 44% in the first half of 2010 to 46% in 2014. Yves-Louis Darricarrère, president of Total’s Exploration & Production Division, said: “Total E&P wants to grow profitably and be one of the best of the majors. To achieve this objective, Total must maximize production from existing fields. This is being done by improving recovery rates from mature fields and by extending production plateaus. Technology and investment are the keywords here.” He said the company plans to bring on stream a large portfolio of projects and that startups between 2010 and 2015 will account for 880,000 BOEPD of production (i.e., approximately 33% of Total’s production in 2015). The main startups between 2011 and 2014 include Trinidad Block 2C, Islay in the North Sea, Usan and Ofon 2 offshore Nigeria, Halfaya in Iraq, Angola LNG, Bongkot South in the Gulf of Thailand, and Kashagan Phase 1 in the Caspian Sea off Kazakhstan. “We must also focus on reserves replacement,” he added. “This means renewing Total’s portfolio by focusing on organic growth (ongoing exploration, access to discovered resources opportunities awaiting development), and completing it with selective acquisitions.”

Clinicopathologic and molecular significance of phospho-Akt expression in early invasive breast cancer

Akt/PKB serine/threonine kinase is a leading signalling modulator for several cellular processes including metabolism, growth, proliferation and survival. However, complexity and diversity in the upstream/downstream arms of Akt pathway, as recent genetic studies reported, challenge considerably the evolvement of effective targeted therapies. The aim was to study the expression of phospho-Akt1 (pAkt) in breast cancer (BC), with respect to different component proteins upstream/downstream of Akt pathway activation, clinicopathologic parameters and patients' outcome. pAkt (Ser473) was evaluated by immunohistochemistry, on tissue microarrays containing 1,202 early invasive BC with long-term clinical follow-up. Seventy-six percent of the studied tumours overexpressed pAkt, where it was associated with expression of oestrogen and androgen receptors, PIK3CA, cytokeratin (CK)18, CK19 and PTEN. Loss of pAkt was correlated with high grade, CK5/6, p53 and high Ki67 labelling index. Higher proportions of luminal tumours were pAkt positive relative to triple negative/basal subtypes. However, pAkt overexpression was not associated with breast cancer specific (BCSS) or metastasis-free survival (MFS). Four tumour phenotypes were identified based on PIK3CA and pAkt expression, with substantial proportions being PIK3CA⁻/pAkt⁺ or PIK3CA⁺/pAkt⁻. These four combinatorial phenotypes were significantly associated with BCSS (p = 0.001) and MFS (p = 0.002). Although pAKT is an oncogene correlated with poor prognostic variables, it was not a prognostic marker. Combinatorial phenotypic groups of PIK3CA/pAkt denoted functional complexity, at translational level, within the upstream and downstream arms of Akt activation with significant impact on patients' outcome. These findings may help development more adequate therapeutic regimens for specific subgroups of this key cancer pathway.

Alarm substance recognition and predator avoidance by chinook salmon (Oncorhynchus tschawytscha) following exposure to an organophosphate pesticide

The sense of smell in fish is thought to be important for behaviors associated with alarm scent recognition and predator avoidance. Olfactory function of juvenile chinook salmon was evaluated in two separate experiments following 2-h immersion exposures to 0, 1, 10, or 100 microg diazinon/L. In the first test system, groups of 10 salmon were transferred to the prechoice zone of a Y-maze fluviarium with parallel streams of water. A dilute alarm scent composed of either chinook skin extract or L-serine was pumped into the water supply of one arm. Fish were allowed to choose either upstream arm by raising a containment screen for 10 min, then their positions were photographed and the screen lowered. In the second test system the relationship of diazinon exposure to predation susceptibility was directly examined by transferring groups of 20 salmon (10 diazinon-exposed, 10 control) to troughs containing a protective cover. These salmon were given two olfactory warnings by delivering conspecific skin extract to both their transfer container and the predation tank they entered. After a 2-min prey acclimation period, larger predator rainbow trout were allowed access to the downstream section of the tank containing the test salmon. The combined fish were observed until approximately 50% of the prey fish had been consumed. Statistical comparisons indicated that although the salmon did avoid the water streams containing alarm scents, none of the diazinon exposure levels resulted in significantly different outcomes from the controls (alpha=0.05) in either the two-choice maze study or the predation study. Possible environmental and population implications are discussed in light of related olfaction and diazinon studies.

Numerical simulation of facet dendritic growth in a forced flow

A numerical simulation based on a new regularized phase-field model is developed to describe the silicon solidification in a forced flow. The effect of forced flow, anisotropy, and mesh grid on dendritic growth shape is investigated. These results indicate that crystals grow into an equiaxial facet dendritic without flow and into an asymmetrical facet dendritic with flow, that is, upstream arm growth is promoted, and downstream inhibited, however, there is no such effect on perpendicular arms. It is also found that the asymmetrical growth feature becomes noticeable with increase in the flow velocity. With the increase in the anisotropy value, the tip velocities of upstream and downstream decrease gradually.

HER2 YVMA drives rapid development of adenosquamous lung tumors in mice that are sensitive to BIBW2992 and rapamycin combination therapy

Mutations in the HER2 kinase domain have been identified in human clinical lung cancer specimens. Here we demonstrate that inducible expression of the most common HER2 mutant (HER2(YVMA)) in mouse lung epithelium causes invasive adenosquamous carcinomas restricted to proximal and distal bronchioles. Continuous expression of HER2(YVMA) is essential for tumor maintenance, suggesting a key role for HER2 in lung adenosquamous tumorigenesis. Preclinical studies assessing the in vivo effect of erlotinib, trastuzumab, BIBW2992, and/or rapamycin on HER2(YVMA) transgenic mice or H1781 xenografts with documented tumor burden revealed that the combination of BIBW2992 and rapamycin is the most effective treatment paradigm causing significant tumor shrinkage. Immunohistochemical analysis of lung tumors treated with BIBW2992 and rapamycin combination revealed decreased phosphorylation levels for proteins in both upstream and downstream arms of MAPK and Akt/mTOR signaling axes, indicating inhibition of these pathways. Based on these findings, clinical testing of the BIBW2992/rapamycin combination in non-small cell lung cancer patients with tumors expressing HER2 mutations is warranted.

Numerical simulation of succinonitrite dendritic growth in a forced flow

Numerical simulation based on phase field method is performed to describe solidification process of pure material in a free or forced flow. The evolution of the interface is showed, and the effects of mesh grid and flow velocity on succinonitrite shape are studied. These results indicate that crystal grows into an equiaxial dendrite in a free flow and into an asymmetrical dendritic in a forced flow. With increasing flow velocity, the upstream dendritic arm tip grows faster and the downstream arm grows slower. However, the evolution of the perpendicular tip has no significant change. In addition, mesh grid has no influence on dendritic growth shape when mesh grid is above 300×300.

Asf1 Is Required for Viability and Chromatin Assembly during DNA Replication in Vertebrate Cells

Asf1 (anti-silencing function 1), a well conserved protein from yeast to humans, acts as a histone chaperone and is predicted to participate in a variety of chromatin-mediated cellular processes. To investigate the physiological role of vertebrate Asf1 in vivo, we generated a conditional Asf1-deficient mutant from chicken DT40 cells. Induction of Asf1 depletion resulted in the accumulation of cells in S phase with decreased DNA replication and increased mitotic aberrancy forming multipolar spindles, leading to cell death. In addition, nascent chromatin in Asf1-depleted cells showed increased nuclease sensitivity, indicating impaired nucleosome assembly during DNA replication. Complementation analyses revealed that the functional domain of Asf1 for cell viability was confined to the N-terminal core domain (amino acids 1-155) that is a binding platform for histones H3/H4, CAF-1p60, and HIRA, whereas Asf1 mutant proteins, abolishing binding abilities with both p60 and HIRA, exhibit no effect on viability. These results together indicate that the vertebrate Asf1 plays a crucial role in replication-coupled chromatin assembly, cell cycle progression, and cellular viability and provide a clue of a possible role in a CAF-1- and HIRA-independent chromatin-modulating process for cell proliferation.

Cloning of biologically active genomes from a Helicoverpa armigera single-nucleocapsid nucleopolyhedrovirus isolate by using a bacterial artificial chromosome

Purification of genotypes from baculovirus isolates provides understanding of the diversity of baculoviruses and may lead to the development of better pesticides. Here, we report the cloning of different genotypes from an isolate of Helicoverpa armigera single-nucleocapsid nucleopolyhedrovirus (HaSNPV) by using a bacterial artificial chromosome (BAC). A transfer vector (pHZB10) was constructed which contained an Escherichia coli mini-F replicon cassette within the upstream and downstream arms of HaSNPV polyhedrin gene. Hz2e5 cells were co-transfected with wild-type HaSNPV DNA and pHZB10 to generate recombinant viruses by homologous recombination. The DNA of budded viruses (BVs) was used to transform E. coli. One of the bacmid colonies, HaBacHZ8, has restriction enzyme digestion profiles similar to an in vivo cloned strain HaSNPV-G4, the genome of which has been completely sequenced. For testing the oral infectivity, the polyhedrin gene of HaSNPV was reintroduced into HaBacHZ8 to generate the recombinant bacmid HaBacDF6. The results of one-step growth curves, electron microscopic examination, protein expression analysis and bioassays indicated that HaBacDF6 replicated as well as HaSNPV-G4 in vitro and in vivo. The biologically functional HaSNPV bacmids obtained in this research will facilitate future studies on the function genomics and genetic modification of HaSNPV.

Visualizing RNA Extrusion and DNA Wrapping in Transcription Elongation Complexes of Bacterial and Eukaryotic RNA Polymerases

Transcription ternary complexes of Escherichia coli RNA polymerase and yeast RNA polymerase III have been analyzed by atomic force microscopy. Using the method of nucleotide omission and different DNA templates, E.coli RNAP has been stalled at position +24, +70 and +379 and RNAP III at position +377 from the starting site. Conformational analysis of E.coli RNAP elongation complexes reveals an average DNA compaction of 22nm and a DNA deformation compatible with ∼180° DNA wrapping against the enzyme. The extent of protein–DNA interaction attributed to wrapping, however, is less than that of corresponding open promoter complexes. DNA wrapping was also observed for RNAP III elongation complexes, which showed a DNA compaction of 30nm. When the RNA polymerases were stalled far from the promoter (+379 and +377), the growing RNA transcript was often visible and it was prevalently seen exiting from the enzyme on the opposite side relative to the smallest angle subtended by the upstream and downstream DNA arms. Surprisingly, we found that many complexes had a second RNAP, not involved in transcription, bound to the growing RNA of a ternary complex. DNA wrapping in the elongation complex suggests a possible mechanism by which the polymerase may overcome the physical barrier to transcription imposed by the nucleosomes.

Efficient adaptive phase field simulation of dendritic growth in a forced flow at low supercooling

Efficient phase field simulation using an adaptive finite volume method is presented for two-dimensional dendritic growth in a forced flow. The extremely large domain (over 2 18 in the ratio of cell size), while keeping very small cell size at the interface, makes the simulation at low supercooling possible. With a strong forced flow, the upstream tip speed reaches a steady state quickly even at low supercooling. The upstream arm develops side branches easily, but remains similar after rescaling, i.e., self-affine, as the diffusive one at steady state.

Primary Cutaneous Microangiopathy in Heart Recipients

In this study we investigated whether a disturbance in microcirculation is detectable in heart recipients with cardiac allograft vasculopathy (CAV) and severe hypercholesterolemia (n = 11) and in 7 heart recipients without CAV in comparison to patients with severe coronary artery disease (n = 49) and age-matched apparently healthy subjects (n = 100). For this purpose, the flow velocity of erythrocytes through cutaneous capillaries at the nail fold of the finger was measured under resting conditions. In addition, reactive hyperemia in the same capillaries after a 3-min ischemia was determined. Patients with CAV and severe lipid disorder showed a pathological reduction in mean capillary erythrocyte velocity under resting conditions with vRBC = 0.10 ± 0.07 mm/s. The latter was significantly and relevantly lower than in patients with coronary three-vessel disease (vRBC = 0.46 ± 0.35 mm/s). It was notable that under resting conditions temporary cessation of flow occurred in 8 of the 11 patients which did not occur in healthy subjects and rarely in patients with three-vessel disease (1 of 49 patients). In comparison to age-matched healthy subjects (vmax = 1.46 ± 0.52 mm/s), the patients with three-vessel disease showed a significant reduction in postischemic maximum erythrocyte velocity (vmax = 0.85 ± 0.55 mm/s), with a considerable shortening of the duration of reactive hyperemia. Patients with CAV demonstrated a total loss of postischemic reactive hyperemia (only 1 of the 11 patients presented a weak reactive hyperemia). Since no macroangiopathy was detectable in the upstream arm arteries, primary cutaneous microangiopathy can be assumed in patients with cardiac allograft vasculopathy and severe hypercholesterolemia.

Evidence for a Mate-Attracting Chemosignal in the Dwarf African Clawed Frog Hymenochirus

Many male frogs and toads possess sexually dimorphic skin glands (breeding glands). However, in most anuran species, the functional significance of the glands is unknown. Here we show that the breeding glands of male dwarf African clawed frogs (Hymenochirus sp.) release a mate-attractant chemosignal. The mate-attractant activity was assessed using a two-choice aquatic Y-maze. Female Hymenochirus were allowed to choose between different treatment waters (e.g., plain water and water housing males) in the upstream arms of the maze, and the females' movements were monitored by computer-linked motion sensors. Females showed a positive chemotaxis to water housing males and to water containing homogenized breeding glands. Females showed no reaction to water housing conspecific females or to water housing breeding gland-ablated males. Additional choice tests demonstrated that females were more attracted to water housing males than to water housing females and to water containing homogenized breeding glands than to water housing breeding gland-ablated males. Males in the maze showed no response to water housing either females or other males, indicating that the attractant is specific for females and is therefore neither a species aggregation signal nor a food-related attractant. These results represent the first experimental demonstration of a mate-attractant function for anuran breeding glands. Because many anuran species possess breeding glands, these results suggest that pheromonal communication could be more widespread among frogs and toads than previously believed.

Numerical simulation of the wind shadow effect on the convective heat transfer to glass bulb sprinklers

A theoretical analysis of the wind shadow effect caused by the arms of the sprinkler frame has been performed using a finite volume computer code. The calculations show that the influence of the arms of the frame upon the convective heat transfer to the bulb is small when the arms of the sprinkler frame and the bulb are orientated perpendicular to the flow. The arms of the frame cause a slight acceleration of the flow around the bulb. Hence, the heat transfer to the bulb in this orientation is somewhat greater than for free flow around a cylinder. In the case when the arms of the sprinkler frame are aligned with the flow, the heat transfer is decreased by approximately a factor of two for the particular geometry considered. This is in agreement with results from wind-tunnel tests for the same geometry. The Nusselt number for this case is still roughly proportional to the square root of the Reynolds number. This finding is of practical importance, as the lumped mass theory for calculating the time to operation of sprinklers relies heavily on the assumption of a square root dependence of the Reynolds number. Good agreement is found between calculated and measured velocity profiles in the region between the glass bulb and the upstream arm of the frame, when the arms are aligned with the airflow.

Chemoattraction between fry of Arctic char [Salvelinus alpinus (L.)] studied in a Y-maze fluviarium

Attraction of fry of Arctic char [Salvelinus alpinus (L.)] to water conditioned by conspecifics of the same age was studied in a Y-maze fluviarium. Two types of experiments were run. In "up-swimming tests" (1), starting from the common leg of the Y-maze, a single fish was given the choice of entering one of the two upstream arms. In "gradient tests" (2), the momentary positions of a single char were time-lapse photographed in a test yard of this common shank. Strong attraction to conditioned water was observed in both types of tests.

An inverted repeat borders a fivefold amplification in satellite DNA.

One variant of a complex satellite DNA of the Bermuda land crab is significantly longer than the average repeat unit of the satellite. The extra DNA in the variant is accounted for by a fivefold tandem amplification of a 0.142-kilobase sequence. The amplified sequence is bounded by a tetranucleotide inverted repeat; the upstream arm of the inverted repeat is missing from two other variants of the satellite. The latter variants contain only one copy of a sequence that is closely related to the amplified sequence. By contrast, in several satellite DNA's of other organisms, extra DNA is inserted.