Efficient synthesis of gaussian filters by cascaded uniform filters

Gaussian filtering is an important tool in image processing and computer vision. In this paper we discuss the background of Gaussian filtering and look at some methods for implementing it. Consideration of the central limit theorem suggests using a cascade of ``simple' filters as a means of computing Gaussian filters. Among ``simple' filters, uniform-coefficient finite-impulse-response digital filters are especially economical to implement. The idea of cascaded uniform filters has been around for a while [13], [16]. We show that this method is economical to implement, has good filtering characteristics, and is appropriate for hardware implementation. We point out an equivalence to one of Burt's methods [1], [3] under certain circumstances. As an extension, we describe an approach to implementing a Gaussian Pyramid which requires approximately two addition operations per pixel, per level, per dimension. We examine tradeoffs in choosing an algorithm for Gaussian filtering, and finally discuss an implementation.     

Investigating T Cell Immunity in Cancer: Achievements and Prospects

T cells play a key role in tumour surveillance, both identifying and eliminating transformed cells. However, as tumours become established they form their own suppressive microenvironments capable of shutting down T cell function, and allowing tumours to persist and grow. To further understand the tumour microenvironment, including the interplay between different immune cells and their role in anti-tumour immune responses, a number of studies from mouse models to clinical trials have been performed. In this review, we examine mechanisms utilized by tumour cells to reduce their visibility to CD8⁺ Cytotoxic T lymphocytes (CTL), as well as therapeutic strategies trialled to overcome these tumour-evasion mechanisms. Next, we summarize recent advances in approaches to enhance CAR T cell activity and persistence over the past 10 years, including bispecific CAR T cell design and early evidence of efficacy. Lastly, we examine mechanisms of T cell infiltration and tumour regression, and discuss the strengths and weaknesses of different strategies to investigate T cell function in murine tumour models.     

Premodification of Pt/γAl2O3 with Cinchonidine for the Enantioselective Hydrogenation of Ethyl Pyruvate: Effect of Premodification Conditions on Reaction Rate and Enantioselection

The premodification of a 5 wt% Pt/-Al₂O₃ catalyst with cinchonidine (0.01 and 0.2 g g^-1 _catalyst) is described and discussed. Premodification is carried out by treating the catalyst with a solution of cinchonidine followed by solvent removal. Catalysts premodified in this way give the same ee and initial rate of reaction for the enantioselective hydrogenation of ethyl pyruvate as those using the standard in situ modification procedure. Investigations of different solvents for premodification and reaction (dichloromethane, ethanol) show that it is the solvent used for the reaction that controls the observed enantioselection. Premodified catalysts also display the initial transient behavior typically observed with in situ modified catalysts in which the ee increases with conversion in the early part of the reaction. Premodified catalysts show an enhanced rate of reaction when ethanol is used as the reaction solvent compared with in situ modified catalysts under the same conditions. Premodification using aerobic conditions gives the best results and premodified catalysts can be stored prior to use for up to a week without loss of catalytic performance.     

Evidence of an oviposition stimulant for peachtree borer

Peachtree borer (PTB) cocoons, peach tree bark, and a mixture of frass and gum obtained arount PTB wounds were extracted with organic solvents of increasing polarity. Female PTB moths,Synanthedon exitiosa (Say), laid the greatest number of eggs on filter paper substrates treated with acetone extracts of PTB cocoons, ethyl acetate extracts of peach tree bark and acetone extracts of frass and gum mixtures. The extracts of cocoons or frass and gum mixture were separated by liquid chromatography and thin layer chromatography.Synanthedon exitiosa (Say).Mention of a commercial or proprietory product does not constitute an endorsement of this product by the USDA.     

Electrothermal study of carbon loaded ethylene-vinylacetate copolymer

Temperature dependence of resistance of carbon black loaded ethylene-vinylacetate (EVA) copolymer was studied from ?100 to 250°C in a modified differential scanning calorimeter (DSC) apparatus. Both room temperature resistivity and positive temperature coefficient of resistance (PTC) effects can be correlated with carbon black parameters (structure, surface area, porosity). Room temperature resistivity and the degree of increase of resistivity, (ratio of maximum to minimum) progressively decrease with carbon black structure if occlusion of polymer by carbon black is considered in calculating the volume fraction. An integrated surface areastructure-porosity equivalence of the carbon black is derived by introducing factors proportional to the volume and porosity of the black used. Any black parameter that increases conductivity (loading, surface area, structure, porosity) decreases the PTC effect. A cable compounder can therefore minimize the undesirable impact of PTC by suitable choice of black-parameters. The necessary considerations for other uses, where PTC effect is used for microswitches, heaters, etc., will be just the opposite. The modified DSC method provides a quick scanning tool for determining the suitability of semicrystalline polymer recipes, either for cable or for any other material using the PTC effect.     

Isolation kernel: the X factor in efficient and effective large scale online kernel learning

Large scale online kernel learning aims to build an efficient and scalable kernel-based predictive model incrementally from a sequence of potentially infinite data points. Current state-of-the-art large scale online kernel learning focuses on improving efficiency. Two key approaches to gain efficiency through approximation are (1) limiting the number of support vectors, and (2) using an approximate feature map. They often employ a kernel with a feature map with intractable dimensionality. While these approaches can deal with large scale datasets efficiently, this outcome is achieved by compromising predictive accuracy because of the approximation. We offer an alternative approach that puts the kernel used at the heart of the approach. It focuses on creating a sparse and finite-dimensional feature map of a kernel called Isolation Kernel. Using this new approach, to achieve the above aim of large scale online kernel learning becomes extremely simple—simply use Isolation Kernel instead of a kernel having a feature map with intractable dimensionality. We show that, using Isolation Kernel, large scale online kernel learning can be achieved efficiently without sacrificing accuracy.

     

Development of a high pressure automated lag time apparatus for experimental studies and statistical analyses of nucleation and growth of gas hydrates

Nucleation in a supercooled or a supersaturated medium is a stochastic event, and hence statistical analyses are required for the understanding and prediction of such events. The development of reliable statistical methods for quantifying nucleation probability is highly desirable for applications where control of nucleation is required. The nucleation of gas hydrates in supercooled conditions is one such application. We describe the design and development of a high pressure automated lag time apparatus (HP-ALTA) for the statistical study of gas hydrate nucleation and growth at elevated gas pressures. The apparatus allows a small volume (≈150 μl) of water to be cooled at a controlled rate in a pressurized gas atmosphere, and the temperature of gas hydrate nucleation, T(f), to be detected. The instrument then raises the sample temperature under controlled conditions to facilitate dissociation of the gas hydrate before repeating the cooling-nucleation cycle again. This process of forming and dissociating gas hydrates can be automatically repeated for a statistically significant (>100) number of nucleation events. The HP-ALTA can be operated in two modes, one for the detection of hydrate in the bulk of the sample, under a stirring action, and the other for the detection of the formation of hydrate films across the water-gas interface of a quiescent sample. The technique can be applied to the study of several parameters, such as gas pressure, cooling rate and gas composition, on the gas hydrate nucleation probability distribution for supercooled water samples.     

Stiction issues and actuation of RF LIGA-MEMS variable capacitors

High aspect ratio variable capacitors have been fabricated using deep X-ray lithography and electroplating. Stiction phenomena applicable to high aspect ratio devices are presented, including the conditions for stiction to occur and the critical dimensions of structures. Actuation tests at 3 GHz are also presented and show a maximum capacitance of 0.86 pF with no actuation voltage and a minimum capacitance of 0.70 pF with an actuation voltage of 20 V just before pull-in, which gives a tuning range of 1.23:1. Corresponding Q-factor values are 49.3 and 70.8 respectively. After pull-in, the measured capacitance is 0.61 pF, corresponding to a tuning range of 1.41:1, with a maximum Q-factor of 102.9.     

The role of anergy in peripheral T cell unresponsiveness

When a T cell's encounter with specific antigen results in good signaling through the T cell antigen receptor yet does not lead to a proliferative response, the T cell enters a state of nonresponsiveness, or anergy. Anergy induction can result from a number of different situations, including antigen presentation by costimulation-deficient or "non-professional" antigen presenting cells, pharmacological blocking of T cell proliferation, or chronic stimulation of the T cell receptor by antigen. Anergy is a long-lived but temporary state characterized by a profound inability of the T cell to produce IL-2. Other effector functions may be affected to variable degrees. Anergy has been characterized most carefully under in vitro conditions, but several experimental models have demonstrated that T cells can also become anergic in vivo. This mechanism for tolerance induction may help to ensure that any mature autoreactive T cells which escape thymic deletion are unable to respond to host tissues. Furthermore, an understanding of the mechanism of anergy induction will most certainly lead to beneficial clinical applications, including improving graft acceptance and avoiding such deleterious immune responses as autoimmunity and allergy.