Numerical Predictions of the Mechanical Properties of A356-SiC Composites Fabricated by Powder Metallurgy

Pure aluminum nanocomposite reinforced with silicon carbide was produced by powder metallurgy process. The mechanical behavior of this composite was modelled and experi-mentally investigated. Measurements of density, tensile properties, and hardness showed that the tensile strength and the porosity of composites increased with an increase in the amount of nanoparticles; however, aluminum ductility decreased. On the other hand, the elongation per-centage remains constant with an increase in the percentage of nanoparticles. Wear resistance of composite samples was higher than that of aluminium alloy. In the current research, a technique based on Artificial Neural Network (ANN) and Finite Element Method (FEM) was applied for the prediction of mechanical properties. It was observed that prediction results obtained in this study are consistent with the real measurements performed on composites

Market Access

The negotiation of improved market access in agriculture is crucial to the success of the Doha Round. The depth of tariff cuts will be the main indication of the level of ambition of the agricultural talks and hence the Round as a whole. Agricultural tariffs remain five times higher than tariffs in industrial goods, and account for the bulk of the distortions in agricultural trade. Recent analysis indicates that 92 percent of the global gains from trade liberalization in agriculture result from removing market access barriers. The July Framework reaffirmed the objective of substantial improvements in market access. This is to be accomplished by a single approach, a tiered (or banded) formula for tariff cuts, with the higher tariff rates being subject to the highest cuts. Negotiations have centered on how many bands to select, where to place the thresholds, and how progressive to make the band-specific reductions. The issue of whether to impose a tariff cap was left undecided in the Framework Agreement. Tariff caps have the advantage of reducing tariffs that are so high that they are little different from an import ban. If the cap is set at a low enough level, real trade improvements may follow. The Framework Agreement specifies that each Member may identify in the schedule a number of products as "Sensitive Products." However, analysis has shown that even exempting as little as two percent of tariff lines from formula based cuts would substantially reduce the expected gains from market access improvements. This points up the need for significant increases in TRQs for Sensitive Products to achieve significant improvements in market access. All tariff lines subject to TRQs, whether or not they are classified as Sensitive Products, should be subject to quota volume expansion. Improving the administration of TRQs and reducing in-quota tariffs are both important objectives for the Doha Round. There is considerable scope to improve the efficiency and transparency of quota regimes. The continued availability of the Special Safeguard for Agriculture by WTO members "remains under negotiation." But abuse of such a safeguard in order to protect domestic producers thwarts the objective of improved market access. Some limitations will need to be introduced if the safeguard is to be continued under the new agreement. The Framework Agreement emphasizes that Special and Differential Treatment is to be an integral part of the market access outcome. This can be ensured by several provisions. Developing countries can specify a number of products as Special Products, based on criteria of food security, livelihood security and rural development needs. The difficulty is in devising concrete criteria for selecting these products. The Framework Agreement also endorses the creation of a Special Safeguard Mechanism for developing countries. Tariff cuts in the Doha Round can erode the value of preferences and can have important consequences for some countries. Preference-granting countries could offset the declining value of those preferences either through financial transfers or additional market access for all products from the current preferred exporters. Least Developed Countries (LDCs) should not be required to undertake any reduction commitments, though they might wish to do so for their own economic advantage. Developed countries should provide duty- and quota-free access to LDCs to encourage full integration into the trade system.International Relations/Trade,

Quick Response Urban Travel Estimation Scenario for the Stillwater Area

Civil Engineerin

Cloning, expression and functional activity of deoxyhypusine synthase from Plasmodium vivax

BACKGROUND: Plasmodium vivax is the most widespread human malaria parasite. However, genetic information about its pathogenesis is limited at present, due to the lack of a reproducible in vitro cultivation method. Sequencing of the Plasmodium vivax genome suggested the presence of a homolog of deoxyhypusine synthase (DHS) from P. falciparum, the key regulatory enzyme in the first committed step of hypusine biosynthesis. DHS is involved in cell proliferation, and thus a valuable drug target for the human malaria parasite P. falciparum. A comparison of the enzymatic properties of the DHS enzymes between the benign and severe Plasmodium species should contribute to our understanding of the differences in pathogenicity and phylogeny of both malaria parasites. RESULTS: We describe the cloning of a 1368 bp putative deoxyhypusine synthase gene (dhs) sequence from genomic DNA of P. vivax PEST strain Salvador I (Accession number AJ549098) after touchdown PCR. The corresponding protein was expressed and functionally characterized as deoxyhypusine synthase by determination of its specific activity and cross-reactivity to human DHS on a Western blot. The putative DHS protein from P. vivax displays a FASTA score of 75 relative to DHS from rodent malaria parasite, P. yoelii, and 74 relative to that from the human parasite, P. falciparum strain 3D7. The ORF encoding 456 amino acids was expressed under control of IPTG-inducible T7 promoter, and expressed as a protein of approximately 50 kDa (theoretically 52.7 kDa) in E. coli BL21 DE3 cells. The N-terminal histidine-tagged protein was purified by Nickel-chelate affinity chromatography under denaturing conditions. DHS with a theoretical pI of 6.0 was present in both eluate fractions. The specific enzymatic activity of DHS was determined as 1268 U/mg protein. The inhibitor, N-guanyl-1, 7-diaminoheptane (GC7), suppressed specific activity by 36-fold. Western blot analysis performed with a polyclonal anti-human DHS antibody revealed cross-reactivity to DHS from P. vivax, despite an amino acid identity of 44% between the proteins. CONCLUSION: We identify a novel DHS protein in the more benign malaria parasite,P. vivax, on the basis of specific enzymatic activity, cross-reactivity with a polyclonal antibody against human DHS, and amino acid identity with DHS homologs from the rodent malaria parasite, P. yoelii, and human P. falciparum strains

Intensity-Weighted Physical Activity Volume and Risk of All-Cause and Cardiovascular Mortality: Does the Use of Absolute or Corrected Intensity Matter?

Background: Previous epidemiological studies examining the association between physical activity (PA) and mortality risk have measured absolute PA intensity using standard resting metabolic rate reference values that fail to consider individual differences. This study compared the risk of all-cause and cardiovascular mortality between absolute and corrected estimates of PA volume. Methods: 49,982 adults aged ≥40 years who participated in the Health Survey for England and Scottish Health Survey in 1994–2008 were included in our study. PA was classified as absolute or corrected metabolic equivalent (MET)-hours per week, taking participant’s weight, height, age, and sex into account. Cox regression models were used to examine the association between absolute and corrected PA volumes and all-cause and cardiovascular mortality. Results: The authors found no difference in the association between levels of PA and risk of all-cause and cardiovascular mortality for absolute and corrected MET-hours per week, although there was a consistent decrease in mortality risk with increasing PA. There was no difference in mortality when analyses were stratified by sex, age, and body mass index. Conclusions: The association between PA volume and risk of mortality was similar regardless of whether PA volume was estimated using absolute or corrected METs. There is no empirical justification against the use of absolute METs to estimate PA volume from questionnaires

Detection of Chlamydia trachomatis and Mycoplasma hominis, genitalium and Ureaplasma urealyticum by polymerase chain reaction in patients with sterile pyuria

Purpose: Chlamydia trachomatis and Mycoplasma hominis, Mycoplasma genitalium, and Ureaplasma urealyticum are associated with various diseases of the urogenital tract, but they are usually not detected by routine microbiological diagnosis

A new method of prenatal alcohol classification accounting for dose, pattern, and timing of exposure: Improving our ability to examine fetal effects from low to moderate exposure

Background: When examining the association between prenatal alcohol exposure and fetal effects, the timing and intensity of exposure have been ignored in epidemiological studies. The effect of using dose, pattern and timing of consumption (“composite” method) was investigated in this study, to examine the association between prenatal alcohol exposure and fetal effects. Methods: The composite method resulted in six categories of exposure (abstinent, low, moderate, binge <weekly, binge 1–2×/week and heavy). The odds of language delay and child behaviour problems were calculated for the composite method and then compared with an analysis using averaged estimates of <1 and 1+ drinks per day and with stratification by quantity ignoring dose per occasion. Data used for the analyses were from a 10% random sample of non-Indigenous women delivering a live infant in Western Australia (1995–1997). Participants from the 1995-1996 cohort were invited to participate in an 8-year longitudinal survey (78% response rate n=2224; 85% were followed-up at 2 years, 73% at 5 years and 61% at 8 years). Results: The effect of moderate and binge levels of exposure was only evident with the composite method; anxiety/depression following first-trimester moderate exposure (OR 2.24, 95% CI 1.16 to 4.34), and following late pregnancy moderate (aggressive behaviour OR 1.93, 95% CI 0.91 to 4.09) and binge (language delay OR 3.00, 95% CI 0.90 to 9.93) exposures. Results for heavy levels of exposure were similar with each method. The estimates for late pregnancy were imprecise due to small numbers. Conclusion: The composite method of classification more closely reflects real-life drinking patterns and better discriminates maternal drinking than the other methods, particularly low, moderate and binge levels

Neutron Capture Cross Sections for the Weak s Process

In past decades a lot of progress has been made towards understanding the main s-process component that takes place in thermally pulsing Asymptotic Giant Branch (AGB) stars. During this process about half of the heavy elements, mainly between 90<=A<=209 are synthesized. Improvements were made in stellar modeling as well as in measuring relevant nuclear data for a better description of the main s process. The weak s process, which contributes to the production of lighter nuclei in the mass range 56<=A<=90 operates in massive stars (M>=8Msolar) and is much less understood. A better characterization of the weak s component would help disentangle the various contributions to element production in this region. For this purpose, a series of measurements of neutron-capture cross sections have been performed on medium-mass nuclei at the 3.7-MV Van de Graaff accelerator at FZK using the activation method. Also, neutron captures on abundant light elements with A<56 play an important role for s-process nucleosynthesis, since they act as neutron poisons and affect the stellar neutron balance. New results are presented for the (n,g) cross sections of 41K and 45Sc, and revisions are reported for a number of cross sections based on improved spectroscopic information