Analysis of spontaneous and double-strand break-induced recombination in rad mutants of S. pombe

Schizosaccharomyces pombe strains containing direct repeats of adeó heteroalleles separated by a functional uro4+ gene, and a DNA site for induction of a double-strand break (DSB), have been used to analyze pathways of spontaneous and DSB-induced intrachromosomal mitotic recombination. These substrates yield Ade+ Ura+ convertants or Ade+ Ura- deletions, by the DSB/gap repair and single-strand annealing (SSA) pathways of recombination, respectively. In S. cerevisiae, the DSB/gap repair pathway is RAD52 dependent, and the RAD1 and RAD10 genes are involved in the SSA pathway. We have sought to understand the genetic control of the pathways of mitotic recombination in S. pombe by determining the effects of mutations in six rad genes involved in DNA repair: rad1 and rad3 involved in checkpoint control in response to unreplicated or damaged DNA; rad5 (homologue of S. cerevisiae RAD3) and rad10 (homologue of S. cerevisiae RAD1) involved in nucleotide excision repair; rad21 and rad22 (homologue of S. cerevisiae RAD52) involved in the repair of ionizing radiation-induced DNA damage. The results suggest that the genetic control of the pathways of spontaneous and DSB-induced mitotic intrachromosomal recombination in S. pombe is different from that in S. cerevisiae.     

Anomalous off-current mechanisms in N-channel poly-Si thin film transistors

The anomalous off-current (I_off) in polysilicon thin film transistors (polysilicon TFTs) is one of the major problems preventing a wide use of these devices in active matrix liquid crystal displays. While previous investigations have focused on the temperature range above 300 K, in this study we have investigated the behaviour of I_off over a wide range of temperatures, namely 180–400 K. The data have been analysed by combining 2D simulations and existing analytic models. By this approach we have identified a pure trap-to-band tunnelling mechanism in polysilicon TFTs and deduced, by a simple procedure, the physical constants. The temperature and bias dependence of the off-current has been explained quantitatively in terms of phonon-assisted tunnelling. The number of generating centres, the dominant trap energy and the thermal capture cross section are deduced from this analysis.     

Predicting heat buildup due to the sun's energy

PVC building products such as siding, windows, and roofings are exposed to the sun. Absorption of the sun's energy leads to a temperature rise, which may cause dimensional control problems, such as expansion and, in severe cases, distortion of the PVC products. The amount of heat buildup in the product depends on the color and/or pigment system of the PVC compound. Generally, the darker the color, the more the sun's energy is absorbed and the higher the temperature heat buildup. Because of the growing demand for darker colors of PVC building products, a test for measuring temperature rise to predict performance of the product in actual use is needed. A laboratory test method for predicting maximum heat buildup due to the sun is described in this paper. The effects of the sample thickness and gloss, carbon black and titanium dioxide levels, and the distance of an infrared heat source from the sample on the heat buildup are also presented in the paper.     

Linearity and sensitivity of MIS position sensitive detectors

The linearity and sensitivity of linear Position Sensitive Detectors (PSD) are the two principal characteristics of sensors to be optimised in sensor fabrication. This work presents several efforts made to understand the internal and external parameters that influence the linearity and sensitivity of Metal Insulator Semiconductor (MIS) linear PSD with an active length of 6 cm. The use of long sensitive areas allows the PSD to achieve greater resolution without the need of a highly accurate light spot integration mechanism. The PSD is built in a multi-layered structure consisting of Cr/a-Si:H (n⁺ doped)/a-Si:H (intrinsic)/SiO_x (passivation layer)/Au, where the active a-Si:H layers were deposited by Modified Triode Plasma Enhanced Chemical Vapour Deposition (MTPECVD), which allows the deposition of good electronic grade material with a low (≈1 × 10¹⁵ cm^{− 3}) defect density inferred by CPM. The sensor linearity and sensitivity shows dependence on the sensor width to length ratio, SiO_x layer and on the value of the load resistance. Sensitivities of more than 30 mV/cm were achieved with linearity near 99%. Besides that, this type of MIS structure allows an improved spectral response in the near-UV region and has its maximum response at 540 nm.     

Weakly useful sequences

An infinite binary sequence x is defined to be

(i) strongly useful if there is a computable time bound within which every decidable sequence is Turing reducible to x; and

(ii) weakly useful if there is a computable time bound within which all the sequences in a non-measure 0 subset of the set of decidable sequences are Turing reducible to x.

Juedes, Lathrop, and Lutz [Theorectical Computer Science 132 (1994) 37] proved that every weakly useful sequence is strongly deep in the sense of Bennett [The Universal Turing Machine: A Half-Century Survey, 1988, 227] and asked whether there are sequences that are weakly useful but not strongly useful. The present paper answers this question affirmatively. The proof is a direct construction that combines the martingale diagonalization technique of Lutz [SIAM Journal on Computing 24 (1995) 1170] with a new technique, namely, the construction of a sequence that is “computably deep” with respect to an arbitrary, given uniform reducibility. The abundance of such computably deep sequences is also proven and used to show that every weakly useful sequence is computably deep with respect to every uniform reducibility.

Poly (vinyl chloride) processing morphology

This paper describes how morphology of PVC changes in the Brabender mixing head. At the range of temperatures used for PVC processing, the Brabender torque-time curve shows minimum torque and maximum torque. The minimum torque is associated with a breakdown of 150 μm PVC grains and 10 μm agglomerates resulting in the release of the 1μm primary particles. The torque increases from minimal interaction between primary particles to the point where primary particles agglomerate at maximum torque so that fibriles can be formed when PVC samples are swollen in acetone and sheard. Further heating reduces the viscosity resulting in lower torque even though residual primary particles still exist with much particle to particle interaction. Primary particle structure disappears at about 215° C with complete melting.     

Formation of poly(butylene terephthalate): growing reactions studied by model molecules

The growing reactions in the formation of poly(butylene terephthalate) have been studied from a kinetic viewpoint with the aid of model molecules. The dependence of the reaction rates on temperature and on the presence of a catalyst (titanium tetrabutylate) and/or of benzoic acid, which shows an inhibition effect, are discussed. A coordinative reaction mechanism is suggested.     

Caffeine (1, 3, 7-trimethylxanthine) in Foods: A Comprehensive Review on Consumption,Functionality, Safety,and Regulatory Matters

ABSTRACT: Caffeine ranks as one of the top most commonly consumed dietary ingredients throughout the world. It is naturally found in coffee beans, cacao beans, kola nuts, guarana berries, and tea leaves including yerba mate. The total daily intake, as well as the major source of caffeine varies globally; however, coffee and tea are the 2 most prominent sources. Soft drinks are also a common source of caffeine as well as energy drinks, a category of functional beverages. Moderate caffeine consumption is considered safe and its use as a food ingredient has been approved, within certain limits, by numerous regulatory agencies around the world. Performance benefits attributed to caffeine include physical endurance, reduction of fatigue, and enhancing mental alertness and concentration. Caffeine has also been recently linked to weight loss and consequent reduction of the overall risks for developing the metabolic syndrome. However, the caloric contribution of caffeine-sweetened beverages needs to be considered in the overall energy balance. Despite all these benefits the potential negative effects of excessive caffeine intake should also be considered, particularly in children and pregnant women.     

Contact effects in organic thin-film transistor sensors

Contact effects in organic thin-film transistors (OTFTs) sensors are here investigated specifically respect to the gate field-induced sensitivity enhancement of more than three orders of magnitude seen in a DHα6T OTFT sensor exposed to 1-butanol vapors. This study shows that such a sensitivity enhancement effect is largely ascribable to changes occurring to the transistor channel resistance. Effects, such as the changes in contact resistance, are seen to influence the low gate voltage regime where the sensitivity is much lower.