4,369 research outputs found

    The Symmetric Group Defies Strong Fourier Sampling

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    The dramatic exponential speedups of quantum algorithms over their best existing classical counterparts were ushered in by the technique of Fourier sampling, introduced by Bernstein and Vazirani and developed by Simon and Shor into an approach to the hidden subgroup problem. This approach has proved successful for abelian groups, leading to efficient algorithms for factoring, extracting discrete logarithms, and other number-theoretic problems. We show, however, that this method cannot resolve the hidden subgroup problem in the symmetric groups, even in the weakest, information-theoretic sense. In particular, we show that the Graph Isomorphism problem cannot be solved by this approach. Our work implies that any quantum approach based upon the measurement of coset states must depart from the original framework by using entangled measurements on multiple coset states

    Toxicity of Tolyltriazole to Bacillus Microorganisms

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    The safety of air travel in cold weather depends upon the use of aircraft deicing fluids (ADAF). The environmental and toxic effects of the ADAF component tolyltriazole are not well understood. Tolyltriazole is a potential human carcinogen and has exhibited microbial toxicity in Microtox test. This research used two methods to investigate the toxicity of tolyltriazole on bacillus shaped microorganisms. The first method compared the dissolved oxygen uptake of microcosms exposed to varying concentrations of tolyltriazole. When exposed to 1000 ppm tolyltriazole, all isolated species showed inhibition in respiration. There was no evidence that tolyltriazole a

    Differential production of superoxide by neuronal mitochondria

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    <p>Abstract</p> <p>Background</p> <p>Mitochondrial DNA (mtDNA) mutations, which are present in all mitochondria-containing cells, paradoxically cause tissue-specific disease. For example, Leber's hereditary optic neuropathy (LHON) results from one of three point mutations mtDNA coding for complex I components, but is only manifested in retinal ganglion cells (RGCs), a central neuron contained within the retina. Given that RGCs use superoxide for intracellular signaling after axotomy, and that LHON mutations increase superoxide levels in non-RGC transmitochondrial cybrids, we hypothesized that RGCs regulate superoxide levels differently than other neuronal cells. To study this, we compared superoxide production and mitochondrial electron transport chain (METC) components in isolated RGC mitochondria to mitochondria isolated from cerebral cortex and neuroblastoma SK-N-AS cells.</p> <p>Results</p> <p>In the presence of the complex I substrate glutamate/malate or the complex II substrate succinate, the rate of superoxide production in RGC-5 cells was significantly lower than cerebral or neuroblastoma cells. Cerebral but not RGC-5 or neuroblastoma cells increased superoxide production in response to the complex I inhibitor rotenone, while neuroblastoma but not cerebral or RGC-5 cells dramatically decreased superoxide production in response to the complex III inhibitor antimycin A. Immunoblotting and real-time quantitative PCR of METC components demonstrated different patterns of expression among the three different sources of neuronal mitochondria.</p> <p>Conclusion</p> <p>RGC-5 mitochondria produce superoxide at significantly lower rates than cerebral and neuroblastoma mitochondria, most likely as a result of differential expression of complex I components. Diversity in METC component expression and function could explain tissue specificity in diseases associated with inherited mtDNA abnormalities.</p

    Population Characteristics of Selected Small Pelagic Fish Species along the Tanzanian Coast

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    Although small pelagic fishing in Tanzania is rising, lack of information on population structure has been a significant concern in its management. This study aimed to determine the species composition, length-weight relationship and length at first maturity of Amblygaster sirm, Encrasicholina heteroloba, Encrasicholina punctifer, Stolephorus commersonii, and Spratelloides gracilis landed at Kilwa Kivinje, Kipumbwi and Shangani along the Tanzanian coast. These landing sites were chosen because of their locations and importance in the small pelagic fishery. Sampling was done monthly from October 2018 to June 2020. The catch composition was site specific such that &nbsp;E. heteroloba dominated at Kilwa Kivinje and Shangani, while E. punctifer dominated at the Kipumbwi site. Further analysis shows allometric coefficient to be greater than 3 for A. sirm and E. punctifer, indicating positive allometric growth, while for S. commersonii and S. gracilis, the allometric coefficient was less than 3, indicating negative allometric growth. Our findings showed that length at first maturity (L50) differed, implying that these species start spawning at different sizes, an essential biological reference for sustainable small pelagic fish exploitation. We recommend seasonal closure of the fishery to maintain reproductive seasons since many species are multiple spawners. Keywords: Population; Small pelagic; Maturity; Tanzani

    Identification of protein complexes with quantitative proteomics in S. cerevisiae

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    Lipids are the building blocks of cellular membranes that function as barriers and in compartmentalization of cellular processes, and recently, as important intracellular signalling molecules. However, unlike proteins, lipids are small hydrophobic molecules that traffic primarily by poorly described nonvesicular routes, which are hypothesized to occur at membrane contact sites (MCSs). MCSs are regions where the endoplasmic reticulum (ER) makes direct physical contact with a partnering organelle, e.g., plasma membrane (PM). The ER portion of ER-PM MCSs is enriched in lipid-synthesizing enzymes, suggesting that lipid synthesis is directed to these sites and implying that MCSs are important for lipid traffic. Yeast is an ideal model to study ER-PM MCSs because of their abundance, with over 1000 contacts per cell, and their conserved nature in all eukaryotes. Uncovering the proteins that constitute MCSs is critical to understanding how lipids traffic is accomplished in cells, and how they act as signaling molecules. We have found that an ER called Scs2p localize to ER-PM MCSs and is important for their formation. We are focused on uncovering the molecular partners of Scs2p. Identification of protein complexes traditionally relies on first resolving purified protein samples by gel electrophoresis, followed by in-gel digestion of protein bands and analysis of peptides by mass spectrometry. This often limits the study to a small subset of proteins. Also, protein complexes are exposed to denaturing or non-physiological conditions during the procedure. To circumvent these problems, we have implemented a large-scale quantitative proteomics technique to extract unbiased and quantified data. We use stable isotope labeling with amino acids in cell culture (SILAC) to incorporate staple isotope nuclei in proteins in an untagged control strain. Equal volumes of tagged culture and untagged, SILAC-labeled culture are mixed together and lysed by grinding in liquid nitrogen. We then carry out an affinity purification procedure to pull down protein complexes. Finally, we precipitate the protein sample, which is ready for analysis by high-performance liquid chromatography/ tandem mass spectrometry. Most importantly, proteins in the control strain are labeled by the heavy isotope and will produce a mass/ charge shift that can be quantified against the unlabeled proteins in the bait strain. Therefore, contaminants, or unspecific binding can be easily eliminated. By using this approach, we have identified several novel proteins that localize to ER-PM MCSs. Here we present a detailed description of our approach

    Surface Buildup Scenarios and Outpost Architectures for Lunar Exploration

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    The Constellation Program Architecture Team and the Lunar Surface Systems Project Office have developed an initial set of lunar surface buildup scenarios and associated polar outpost architectures, along with preliminary supporting element and system designs in support of NASA's Exploration Strategy. The surface scenarios are structured in such a way that outpost assembly can be suspended at any time to accommodate delivery contingencies or changes in mission emphasis. The modular nature of the architectures mitigates the impact of the loss of any one element and enhances the ability of international and commercial partners to contribute elements and systems. Additionally, the core lunar surface system technologies and outpost operations concepts are applicable to future Mars exploration. These buildup scenarios provide a point of departure for future trades and assessments of alternative architectures and surface elements

    Rift Valley fever potential mosquito vectors and their infection status in Ngorongoro District in northern Tanzania

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    Background: Rift Valley fever (RVF) is a mosquito-borne viral zoonotic disease. Rift Valley fever virus (RVFV) has been isolated from more than 40 species of mosquitoes from eight genera. This study was conducted to determine the abundance of potential mosquito vectors and their RVFV infection status in Ngorongoro District of northern Tanzania.Methods: Adult mosquitoes were collected outdoors using the CDC light traps baited with carbon dioxide in five randomly selected villages namely, Meshili, Malambo, Osinoni, Endulen and Nainokanoka. The study was carried out towards the end of rainy season in May 2013. The traps were set in proximity to potential breeding sites and cattle kraals. The collected mosquitoes were identified to genus and species using morphological keys. They were tested for RVFV RNA  using  real time reverse transcription-polymerase chain reaction (rRT-PCR).Results: A total of 2,094 adult mosquitoes belonging to three genera and nine species were collected. Most of them (87.5%) were collected in Meshili, followed by Malambo (8.2%) and Osinoni (4%) villages. No single mosquito was collected in Nainokanoka or Endulen. The nine species collected were Culex pipiens complex, Cx. antennatus, Cx. tigripes, Cx. annulioris, Cx. cinereus, Anopheles arabiensis, An. squamosus, An. pharoensis and Mansonia uniformis. No RVFV RNA was detected in the mosquito specimens.Conclusion: Various RVFV potential mosquito species were collected from the study villages. These mosquito vectors were heterogeneously distributed in the district suggesting a variation in RVF transmission risk in the study area

    Protection Against a Bovine Viral Diarrhea Virus (BVDV) Type 1 Challenge in Calves Vaccinated with a Bovine Herpesvirus-1 (BHV-1)-BVDV Recombinant

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    A recently developed recombinant bovine herpesvirus 1 (BHV-1) virus containing the envelope protein gp53 of bovine viral diarrhea virus (BVDV) type 1, BHV-1 (v1V31), was assessed for its ability to protect against BVDV in calves. Four calves were vaccinated intranasally with the recombinant BHV-1-BVDV vaccine and did not exhibit any clinical signs following vaccination. The vaccine virus was recovered from all vaccinated calves on days 8 through 10 and the replication appeared to be restricted to nasal passages. Twenty-eight days after vaccination, the four vaccinated and four control calves were challenged with the type 1 BVDV, strain NY-1. All calves had slight temperature elevations but the clinical signs were more severe in the control calves. The platelet counts were significantly depressed in the control calves. Prior to challenge, neither group had BVDV serum neutralizing antibody. The vaccinated calves developed higher serum antibody levels 2 months following challenge, indicating a secondary immune response. Necropsy was performed six weeks following infection. No latent BHV-1 virus was detected from the trigeminal ganglion of any of the vaccinated calves. The recombinant BHV-1 virus vaccine containing a single BVDV protein provided partial protection against BVDV infection
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