An investigation into unsteady base bleed for drag reduction in bluff two-box SUVs

This paper discusses a preliminary investigation into the use of base bleed on a production SUV using CFD analysis. The paper shows the methods used in creating the computational model and conducting the analysis, and present the findings to date. The paper shows that the reduction in drag increases as the mass flow rate of air is increased when the flow is deflected at the outlet. By controlling the turbulent wake to the rear of the vehicle, it is shown in the paper that mass flow rates of under 2kg/s can reduce drag coefficient by 8.2% with an outlet on the side of the vehicle, and that a mass flow rate of under 1.5kg/s can reduce the drag coefficient by 10.7% for an outlet on the upper section of the rear of the vehicle. The paper also discusses the feasibility of base bleed being applied to a production vehicle

Expedited Injustice: The Problems Regarding the Current Law of Expedited Removal of Aggravated Felons

Following the attacks of September 11, 2001, he and his family, like many Americans of the Islamic faith, felt persecuted by their neighbors, despite having had nothing to do with the terrorist attacks on the World Trade Center and the Pentagon.\u27 Mr. Rashid felt intimidated by people following him and calling his home to accuse him of complicity in the September 11 attacks. After weeks of harassment, Mr. Rashid\u27s family contacted the police. Unfortunately for Mr. Rashid, however, he shared a name with a suspected terrorist. Thus, instead of addressing Rashid\u27s concerns, the U.S. government began to suspect him as well. Then, on April 17, 2003, Rashid was involved in a physical confrontation with some of the same local troublemakers who had been harassing his family during the previous two years. He claimed self-defense, but the prosecutor disagreed and charged him with third-degree assault, a misdemeanor, for which he was sentenced to 401 days in prison, most of which was suspended. Despite his relatively minor offense (he served well under one year in jail), the crime constituted an aggravated felony under federal immigration law. This meant that the government could deport Mr. Rashid without the procedural safeguards normally available to those facing deportation through a process known as expedited removal. The government wanted to separate Mr. Rashid from his home and family even though the law appeared unjustly applied in his case.\u27 Mr. Rashid had done nothing but share the name of a noted terrorist, yet the government singled him out for persecution under an overly broad immigration law.\u2

Measurement of retinal vessel widths from fundus images based on 2-D modeling

Changes in retinal vessel diameter are an important sign of diseases such as hypertension, arteriosclerosis and diabetes mellitus. Obtaining precise measurements of vascular widths is a critical and demanding process in automated retinal image analysis as the typical vessel is only a few pixels wide. This paper presents an algorithm to measure the vessel diameter to subpixel accuracy. The diameter measurement is based on a two-dimensional difference of Gaussian model, which is optimized to fit a two-dimensional intensity vessel segment. The performance of the method is evaluated against Brinchmann-Hansen's half height, Gregson's rectangular profile and Zhou's Gaussian model. Results from 100 sample profiles show that the presented algorithm is over 30% more precise than the compared techniques and is accurate to a third of a pixel

FTIR-DRIFTS-based prediction of β-carotene, α-tocopherol and L-ascorbic acid in mango (Mangifera indica L.) fruit pulp

Mango fruits contain substantial vitamins and dietary fibre. Vitamins vary among and within fruits depending on cultivar type and ripening stage. Conventional techniques of vitamins analysis are based on High Pressure Liquid Chromatography, which are costly and laborious. This study evaluated the potential of Fourier transform infrared-diffuse reflectance spectroscopy (FTIR-DRIFTS) technique in predicting β-carotene, α-tocopherol and L-ascorbic acid in pulps of four mango cultivar types (‘Apple’, ‘Kent’, ‘Ngowe’, and ‘Tommy Atkins’). Combination of ran dom forest (RF) and first derivative spectra developed the predictive models. Factorial ANOVA examined the interaction effect of cultivar type, site (‘Thika’, ‘Embu’ and ‘Machakos), and fruit canopy position (sun exposed/within crown) on β-carotene, α-tocopherol and L-ascorbic acid contents. RF Models gave R2 = 0.97, RMSE = 2.27, RPD = 0.72 for β-carotene; R2 = 0.98, RMSE = 0.26, RPD = 0.30 for α-tocopherol and R2 = 0.96, RMSE = 0.51, RPD = 1.96 for L-ascorbic acid. Generally cultivar type affected vitamin C, F (3, 282) = 7.812, p < 0.05. Apple and Tommy Atkins had higher mean vitamins than Ngowe and Kent. In Machakos, within canopy fruits had higher β-carotene than sun-exposed fruits, F (5, 257) = 2.328, p = 0.043. However, interactions between fruit position, site and cultivar did not affect α-tocopherol and vitamin C. In Thika, Tommy Atkins at fully ripe stage had higher vitamin C than at intermediate maturity stage, F (2, 143) = 7.328, p = 0.01. These results show that FTIR-DRIFTS spectroscopy is a high-throughput method that can be used to predict mango fruit vitamins of in a large data set

A simple field based method for rapid wood density estimation for selected tree species in Western Kenya

Wood density is an important variable for accurate quantification of woody biomass and carbon stocks. Conventional destructive methods for wood density estimation are resource intensive, prohibiting their use, limiting the application of approaches that would minimize uncertainties in tree biomass estimates. We tested an alternative method involving tree coring with a carpenter's auger to estimate wood density of seven tropical tree species in Western Kenya. We used conventional water immersion method to validate results from the auger core method. The mean densities (and 95% confidence intervals) ranged from 0.36 g cm−3 (0.25–0.47) to 0.67 g cm−3 (0.61–0.73) for the auger core method, and 0.46 g cm−3 (0.42–0.50) to 0.67 g cm−3 (0.61–0.73) for the water immersion method. The auger core and water immersion methods were not significantly different for four out of seven tree species namely; Acacia mearnsii, Mangifera indica, Eucalyptus grandis and Grevillea robusta. However, wood densities estimated from the auger core method were lower (t (61) = 7.992, P = <0.001). The ease of the auger core method application, as a non-destructive method in acquiring wood density data, is a worthy alternative in biomass and carbon stocks quantification. This method could protect trees outside forests found in most parts of Africa

Optic nerve head segmentation

Reliable and efficient optic disk localization and segmentation are important tasks in automated retinal screening. General-purpose edge detection algorithms often fail to segment the optic disk due to fuzzy boundaries, inconsistent image contrast or missing edge features. This paper presents an algorithm for the localization and segmentation of the optic nerve head boundary in low-resolution images (about 20 /spl mu//pixel). Optic disk localization is achieved using specialized template matching, and segmentation by a deformable contour model. The latter uses a global elliptical model and a local deformable model with variable edge-strength dependent stiffness. The algorithm is evaluated against a randomly selected database of 100 images from a diabetic screening programme. Ten images were classified as unusable; the others were of variable quality. The localization algorithm succeeded on all bar one usable image; the contour estimation algorithm was qualitatively assessed by an ophthalmologist as having Excellent-Fair performance in 83% of cases, and performs well even on blurred image

A high-throughput, quantitative cell-based screen for efficient tailoring of RNA device activity

Recent advances have demonstrated the use of RNA-based control devices to program sophisticated cellular functions; however, the efficiency with which these devices can be quantitatively tailored has limited their broader implementation in cellular networks. Here, we developed a high-efficiency, high-throughput and quantitative two-color fluorescence-activated cell sorting-based screening strategy to support the rapid generation of ribozyme-based control devices with user-specified regulatory activities. The high-efficiency of this screening strategy enabled the isolation of a single functional sequence from a library of over 106 variants within two sorting cycles. We demonstrated the versatility of our approach by screening large libraries generated from randomizing individual components within the ribozyme device platform to efficiently isolate new device sequences that exhibit increased in vitro cleavage rates up to 10.5-fold and increased in vivo activation ratios up to 2-fold. We also identified a titratable window within which in vitro cleavage rates and in vivo gene-regulatory activities are correlated, supporting the importance of optimizing RNA device activity directly in the cellular environment. Our two-color fluorescence-activated cell sorting-based screen provides a generalizable strategy for quantitatively tailoring genetic control elements for broader integration within biological networks

A versatile cis-blocking and trans-activation strategy for ribozyme characterization

Synthetic RNA control devices that use ribozymes as gene-regulatory components have been applied to controlling cellular behaviors in response to environmental signals. Quantitative measurement of the in vitro cleavage rate constants associated with ribozyme-based devices is essential for advancing the molecular design and optimization of this class of gene-regulatory devices. One of the key challenges encountered in ribozyme characterization is the efficient generation of full-length RNA from in vitro transcription reactions, where conditions generally lead to significant ribozyme cleavage. Current methods for generating full-length ribozyme-encoding RNA rely on a trans-blocking strategy, which requires a laborious gel separation and extraction step. Here, we develop a simple two-step gel-free process including cis-blocking and trans-activation steps to support scalable generation of functional full-length ribozyme-encoding RNA. We demonstrate our strategy on various types of natural ribozymes and synthetic ribozyme devices, and the cleavage rate constants obtained for the RNA generated from our strategy are comparable with those generated through traditional methods. We further develop a rapid, label-free ribozyme cleavage assay based on surface plasmon resonance, which allows continuous, real-time monitoring of ribozyme cleavage. The surface plasmon resonance-based characterization assay will complement the versatile cis-blocking and trans-activation strategy to broadly advance our ability to characterize and engineer ribozyme-based devices

Cellulose biosynthesis by enzymes from the hypocotyl of the mung bean (Phaseolus aureus), as judged by the extraction technique of Updegraff (1969)

The numbers refer to the chapters concerned. 1. Current knowledge on cellulose biosynthesis was summarised. The section is divided into four main parts concerned with; A. the importance of cellulose; B. the structure of cellulose; C . cellulose biosynthesis, and; D. the cellular location of cellulose biosynthesis. Where relevant, cellulose biosynthesis in the cellulosic bacterium Acetobacten xylinum and algal systems was included. 2. This chapter presents the rationale behind this work and the criteria used to assess the cellulosic nature of the synthesised products. 3. The materials and methods used in this work were described. 4. The incorporation of radioactivity from GDP-[U-14C]-G, UDP-[U-14G]-G, [U-14C]-sucrose, [U-14C]-glucose and [U-14C]-glucose-1-phosphate into the water-and chloroform: methanol (3:2 v/v)-insoluble products was investigated. It was found that the sugar-nucleotides were the most efficient substrates, that the incorporation of radioactivity from 1.0 mM UDP-[U-14c]-G into these products appeared to be substrate-activated, and that the products synthesised from UDP-[U-14C]-G at this concentration contained beta (1-3) linked glucose. The distribution of the enzymic activity utilising the sugar-nucleotides between wall and particulate fractions and the effect of storage of the enzymes at -20°C was also investigated. 5. The alpha-cellulose extraction was explained. Radioactivity from GDP-[U-14]-G, GDP-[U-14C]-M and UDP-[U-14C]-G was incorporated into alpha-cellulose. GDP-[U-14C]-M was found to be an efficient substrate and GDPM stimulated the incorporation of radioactivity from GDP-[U-14C]-G into this fraction. 6. The Updegraff extraction was introduced. Both UDP-[U-14C]-G and GDP-[U-14C]-G acted as substrates for Updegraff cellulose (U-cellulose) synthesis. The effect of prolonged periods of extraction of the water-and chloroform : m ethanol (3:2 v/v)-insoluble products in the Updegraff reagent and the effect of retaining the enzymes at -20 °C was studied. 7. The incorporation of radioactive glucose from GDP- [U-14C]-G (particularly at higher concentrations than that traditionally used by previous researchers) and GDP- [U-14C]-M into U-cellulose was studied. The factors involved in the cessation of U-cellulose synthesis from GDP-[U-14C]-G were investigated and discussed. The products appear to be glucomannan (on the basis of a kinetic study of the effect of GDPM on U-cellulose synthesis from GDP-[U-14C]-G, structural and gel-filtration studies) and possibly mannan (on the basis of a time course study on the synthesis of U-cell- ulose from 102 muM GDP- [U-14C]-M) and glucan (based on a time-course study of U-cellulose synthesis from 1.0 mM GDP-[U-14C]-G, the effect of E D T A on U-cellulose synthesis from GDP- [U-14Cl-G and GDP-[U-14C]-M, and a structural study). There was some indication of the presence of a substrate-activated enzyme which synthesised pure glucan from GDP-[U-14C]-G. The non-glucan products could not be solubilised even after prolonged periods of extraction in Updegraff reagent. 8. The incorporation of radioactive glucose from 1-5 muM UDP-[U-14C]-G into U-cellulose was further investigated. The synthesis of U-cellulose from 1 muM UDP-[U-14C]-G showed no distinct pH optimum in the range 4-11 and the factors involved in the cessation of the reaction were discussed. Gel filtration of the water and chloroform : methanol (3:2 v/v)-insoluble products suggested that the majority of the products had a molecular weight of less than 7 x 10

Spin-gap opening accompanied by a strong magnetoelastic response in the S=1 magnetic dimer system Ba3BiRu2O9

Neutron diffraction, magnetization, resistivity, and heat capacity measurements on the 6H-perovskite Ba3BiRu2O9 reveal simultaneous magnetic and structural dimerization driven by strong magnetoelastic coupling. An isostructural but strongly displacive first-order transition on cooling through T*=176 K is associated with a change in the nature of direct Ru-Ru bonds within Ru2O9 face-sharing octahedra. Above T*, Ba3BiRu2O9 is an S=1 magnetic dimer system with intradimer exchange interactions J0/kB=320 K and interdimer exchange interactions J'/kB=-160 K. Below T*, a spin-gapped state emerges with \Delta\approx220 K. Ab initio calculations confirm antiferromagnetic exchange within dimers, but the transition is not accompanied by long range-magnetic order.Comment: 5 pages, 5 figures, accepted by Physical Review