The Effect of Ultraviolet Light on the Color of Unbleached Pulps: Literature Survey

A literature survey was prepared which covered the published information on the effects of ultraviolet light on the color of unbleached pulps. Experiments were conducted with eight types of unbleached pulp which were converted into optical test pads under varying pH conditions, using sulphuric acid and caustic soda as well as alum and sodium aluminate for adjustment of the hydrogen ion concentration. The optical test pads were exposed to ultraviolet irradiation. Thereafter, reflectance measurements were taken, covering the range of visible light. From the limited number of experiments which were conducted we can conclude that: 1. Unbleached coniferous kraft, unbleached hardwood, sulphite, and unbleached hardwood soda pulps brightened when exposed to ultraviolet light. 2. Unbleached hardwood H.S.S.C. (70% yield), unbleached hardwood N.S.S.C. (78% yield), unbleached coniferous sulphite, unbleached hardwood cold soda, and unbleached hardwood chemi-groundwood pulps yellowed when exposed to ultraviolet light. 3. Adjusting the pH four with sulphuric acid increased the reflectance of most pulps while adjusting the pH to ten with sodium hydroxide decreased the reflectance of the pulps. This was observed before irradiation with ultraviolet light. 4. When papermakers\u27 alum was used to adjust the pH of the sheets to four, the reflectance values before irradiation decreased slightly in most cases. There was a larger drop in the reflectance value when the pH of the pulp is adjusted to the pH ten with sodium aluminate. 5. Both means of adjusting the pH to ten, namely sodium hydroxide and sodium aluminate, decreased the initial brightness of the pulp. However, there was little correlation between the effects of the two compounds used to adjust the pulp pH to four, namely sulphuric acid and papermakers\u27 alum. 6. Experimental results showed that none of the compounds used in pH control stabilized consistently the color of unbleached pulp exposed to ultraviolet irradiation

A distributional model of semantic context effects in lexical processinga

One of the most robust findings of experimental psycholinguistics is that the context in which a word is presented influences the effort involved in processing that word. We present a novel model of contextual facilitation based on word co-occurrence prob ability distributions, and empirically validate the model through simulation of three representative types of context manipulation: single word priming, multiple-priming and contextual constraint. In our simulations the effects of semantic context are mod eled using general-purpose techniques and representations from multivariate statistics, augmented with simple assumptions reflecting the inherently incremental nature of speech understanding. The contribution of our study is to show that special-purpose m echanisms are not necessary in order to capture the general pattern of the experimental results, and that a range of semantic context effects can be subsumed under the same principled account.›

Interventions for neurocognitive dysfunction

Purpose of review: To evaluate current barriers to HIV cure strategies and interventions for neurocognitive dysfunction with a particular focus on recent advancements over the last three years. Recent findings: Optimal anti-retroviral therapy (ART) poses challenges to minimise neurotoxicity, whilst ensuring blood brain barrier penetration and minimising the risk of cerebrovascular disease. CSF biomarkers, BCL11B and neurofilament light chain may be implicated with a neuroinflammatory cascade leading to cognitive impairment. Diagnostic imaging with diffusion tensor imaging as well as resting-state fMRI show promise in future diagnosis and monitoring of HAND. Summary: The introduction of ART has resulted in a dramatic decline in HIV-associated dementia. Despite this reduction, milder forms of HIV-associated neurocognitive disorder (HAND) are still prevalent and are clinically significant. The central nervous system (CNS) has been recognised as a probable reservoir and sanctuary for HIV, representing a significant barrier to management interventions

Enabling rural broadband via TV "white space"

The use of multiple frequency bands within a wireless network allows the advantages of each band to be exploited. In this paper we discuss how HopScotch, a rural wireless broadband access test bed running in the Scottish Highlands and Islands, uses both 5 GHz and ultra high frequency "white space" bands to offer large data rates and expansive coverage whilst reducing the number of base stations or required transmission power. This reduction in energy consumption allows HopScotch to provide a low-cost and green solution for rural broadband delivery

"WindFi" - a renewable powered base station for rural broadband

The HopScotch rural wireless broadband access test bed uses a network of low power base stations, powered by renewable energy sources to provide a low-cost rural broadband solution. In this paper we discuss the low power design aspects of the HopScotch base station and the impact on the required generation potential of renewable sources, battery bank sizing and the use of tracking PV arrays

Wakabi: on-demand ride service for rural Uganda

In Uganda, the majority of the population lives in rural villages that rely on last-mile distribution for goods such as vaccines, fresh water, trade goods, and other forms of humanitarian relief. Last-mile distribution refers to the last mile (or few miles) that goods must be transported in order to reach their final destination from a main delivery hub. Coordination is one of the primary issues that exist when trying to solve the last-mile problem. In this paper we present our solution to this problem: an SMSbased, on-demand ride-sharing service designed to empower the people of rural Uganda by helping organize the transport of both people and goods. Our application functions similarly to the popular ride-sharing app Uber or Lyft but does not require a smartphone to use. Users text a predefined number to request a ride, get paired with a nearby boda-boda driver (these motorcycle drivers currently offer ride-sharing services to rural Ugandans by word-of-mouth), and are transported to their destination. The service also allows users to specify trailer requirements in case they need to transport goods as well. By building Wakabi around the existing boda-boda system we are not only helping to coordinate last-mile distribution efforts, but are also improving the efficiency of the existing boda-boda drivers that provide transportation to rural Ugandans. Following the 20142015 academic year, Fulbright Scholar and business partner Ty Van Herweg will be responsible for both testing and deploying Wakabi in Uganda. We hope that our application will help boda-boda drivers better serve their riders, and provide businesses with an ideal and cost-effective last-mile distribution solution

Oxygen and tissue culture affect placental gene expression

Introduction Placental explant culture is an important model for studying placental development and functions. We investigated the differences in placental gene expression in response to tissue culture, atmospheric and physiologic oxygen concentrations. Methods Placental explants were collected from normal term (38–39 weeks of gestation) placentae with no previous uterine contractile activity. Placental transcriptomic expressions were evaluated with GeneChip® Human Genome U133 Plus 2.0 arrays (Affymetrix). Results We uncovered sub-sets of genes that regulate response to stress, induction of apoptosis programmed cell death, mis-regulation of cell growth, proliferation, cell morphogenesis, tissue viability, and protection from apoptosis in cultured placental explants. We also identified a sub-set of genes with highly unstable pattern of expression after exposure to tissue culture. Tissue culture irrespective of oxygen concentration induced dichotomous increase in significant gene expression and increased enrichment of significant pathways and transcription factor targets (TFTs) including HIF1A. The effect was exacerbated by culture at atmospheric oxygen concentration, where further up-regulation of TFTs including PPARA, CEBPD, HOXA9 and down-regulated TFTs such as JUND/FOS suggest intrinsic heightened key biological and metabolic mechanisms such as glucose use, lipid biosynthesis, protein metabolism; apoptosis, inflammatory responses; and diminished trophoblast proliferation, differentiation, invasion, regeneration, and viability. Discussion These findings demonstrate that gene expression patterns differ between pre-culture and cultured explants, and the gene expression of explants cultured at atmospheric oxygen concentration favours stressed, pro-inflammatory and increased apoptotic transcriptomic response

Elevated histamine model: a protocol for an ex vivo model for in vitro study of histamine effect on placenta

Maternal plasma histamine levels in normal pregnancy are generally similar to those in non pregnant women during the first trimester, and usually decline gradually during the 2nd and 3rd trimesters (Brew and Sullivan, 2006). In some complications of pregnancy such as hyperemesis gravidarum (HG), spontaneous abortion (SA), pre-term labour (PL) and Pre-eclampsia (PE) histamine levels increase as pregnancy proceeds (Southren et al., 1966; Achari, Achari and Rao, 1971; Beaven et al., 1975), and the elevated levels of histamine may directly cause some of the features of these disorders (Brew and Sullivan, 2006). Placenta is a major source of histamine, but it also releases active diamine amine oxidase (DAO; EC 1.4.3.22) into the maternal circulation, which metabolises histamine (Kapeller-Adler, 1944; Gunther and Glick, 1967; Semeniuchenko, 1975; Granerus, Gillbrand and Wetterqvist, 1977; Purcell and Hanahoe, 1991; Brew, Lakasing and Sullivan, 2007). This breaks down the histamine released from the placenta in normal pregnancy, leading to the limited changes in maternal blood histamine. Clinically, the deported placental DAO activity in maternal blood increases a 1000 fold during normal pregnancy (Southren et al., 1966). The DAO activity rises exponentially in the first 24 weeks of normal gestation and plateaus thereafter to form a normal histamine-DAO-axis (nHDA) (Southren et al., 1966; Beaven et al., 1975; Dubois et al., 1977) (Ahlmark, 1944; Southren et al., 1966; Gunther and Glick, 1967; Weingold and Southren, 1968; Tufvesson, 1978; Beaven et al., 1975; Dubois et al., 1977). In contrast, the spontaneous exponential rise of DAO activity is abrogated from gestational week 8 onwards thus, leading to a defective Histamine-DAO-Axis (dHDA) in pregnancies that present with elevated maternal blood histamine (Southren et al., 1966; Achari, Achari and Rao, 1971; Beaven et al., 1975; Legge and Duff, 1981). Ex-vivo defective Histamine-DAO-Axis also referred to Elevated Histamine Model (EHM) was developed to mimic in vivo dHDA to study effects of histamine in human placenta. The EHM was developed by creating in vitro culture model to represent normal placentae with nHDA and complicated placentae with dHDA. In the nHDA samples, the endogenous DAO activity is maintained to eliminate endogenous production of histamine, while DAO activity is blocked with aminoguanidine in the dHDA samples to allow histamine levels to elevate during the treatment period. Aminoguanidine is a specific inhibitor of DAO enzyme activity (Tamura et al., 1989)