Understanding the disorder of the DNA base cytosine on the Au(111) surface

Using ultrahigh vacuum scanning tunneling microscopy (STM) and ab initio density functional theory, we have investigated in detail structures formed by cytosine on the Au(111) surface in clean ultrahigh vacuum conditions. In spite of the fact that the ground state of this DNA base on the surface is shown to be an ordered arrangement of cytosine one-dimensional branches (filaments), this structure has never been observed in our STM experiments. Instead, disordered structures are observed, which can be explained by only a few elementary structural motifs: filaments, five- and sixfold rings, which randomly interconnect with each other forming bent chains, T junctions, and nanocages. The latter may have trapped smaller structures inside. The formation of such an unusual assembly is explained by simple kinetic arguments as a liquid-glass transition. © 2008 American Institute of Physics

Green, Yellow, and Red risk perception in everyday life - a communication tool

Background: Adolescents have the highest risk for food allergy-related fatalities. Our main aim was to investigate the level of risk in everyday social situations as perceived by adolescents/young adults with peanut allergy, their families, and their friends. Methods: The web-based ‘Colours Of Risks’ (COR) questionnaire was completed by 70 patients (aged 12–23 years), 103 mothers and fathers, 31 siblings (aged 12–26 years), and 42 friends (aged 12–24 years). COR deals with six main contexts (home, school/university, work, visiting/social activities, special occasions/parties, and vacations), each with 1-12 items. Response categories are green (I feel safe), yellow (I feel uncertain), or red (I feel everything is risky). Results: There was a high level of agreement between participants in defining situations as safe, uncertain, or risky, but female patients and mothers rated fewer situations as safe compared to male patients and fathers. Being with close friends and family, and attending planned parties without alcohol were perceived as situations of low risk. While 94% of patients took an epinephrine auto-injector (EAI) into risky situations, only 65% took it into safe situations. In contrast to the close family, 31% of the friends did not know the patient had an EAI, and fewer knew how to administer the EAI. Conclusion: Young adults with peanut allergy face challenges when moving from the safe home with ready assistance if needed, to independence with unpredictable surroundings and less certain help. Perceived ‘safe’ situations may in fact be the riskiest, as patients often do not take the EAI with them

Quality of life in childhood, adolescence and adult food allergy: patient and parent perspectives

Background: Studies of children with food allergy typically only include the mother and have not investigated the relationship between the amount of allergen needed to elicit a clinical reaction (threshold) and health-related quality of life (HRQL). Our aims were (i) to compare self-reported and parent-reported HRQL in different age groups, (ii) to evaluate the impact of severity of allergic reaction and threshold on HRQL, and (iii) to investigate factors associated with patient-reported and parent-reported HRQL. Methods: Age-appropriate Food Allergy Quality of Life Questionnaires (FAQLQ) were completed by 73 children, 49 adolescents and 29 adults with peanut, hazelnut or egg allergy. Parents (197 mothers, 120 fathers) assessed their child's HRQL using the FAQLQ-Parent form. Clinical data and threshold values were obtained from a hospital database. Significant factors for HRQL were investigated using univariate and multivariate regression. Results: Female patients reported greater impact of food allergy on HRQL than males did. Egg and hazelnut thresholds did not affect HRQL, but lower peanut threshold was associated with worse HRQL. Both parents scored their child's HRQL better than the child's own assessment, but whereas mother-reported HRQL was significantly affected by limitations in the child's social life, father-reported HRQL was affected by limitations in the family's social life. Severity of allergic reaction did not contribute significantly to HRQL. Conclusion: The risk of accidental allergen ingestion and limitations in social life are associated with worse HRQL. Fathers provide a unique perspective and should have a greater opportunity to contribute to food allergy research

Remote sensing, geographical information system and spatial analysis for schistosomiasis epidemiology and ecology in Africa

Beginning in 1970, the potential of remote sensing (RS) techniques, coupled with geographical information systems (GIS), to improve our understanding of the epidemiology and control of schistosomiasis in Africa, has steadily grown. In our current review, working definitions of RS, GIS and spatial analysis are given, and applications made to date with RS and GIS for the epidemiology and ecology of schistosomiasis in Africa are summarised. Progress has been made in mapping the prevalence of infection in humans and the distribution of intermediate host snails. More recently, Bayesian geostatistical modelling approaches have been utilized for predicting the prevalence and intensity of infection at different scales. However, a number of challenges remain; hence new research is needed to overcome these limitations. First, greater spatial and temporal resolution seems important to improve risk mapping and understanding of transmission dynamics at the local scale. Second, more realistic risk profiling can be achieved by taking into account information on people's socio-economic status; furthermore, future efforts should incorporate data on domestic access to clean water and adequate sanitation, as well as behavioural and educational issues. Third, high-quality data on intermediate host snail distribution should facilitate validation of infection risk maps and modelling transmission dynamics. Finally, more emphasis should be placed on risk mapping and prediction of multiple species parasitic infections in an effort to integrate disease risk mapping and to enhance the cost-effectiveness of their contro

Theory of adsorbate induced surface reconstruction on W(100)

We report results of a theoretical study on an adsorbate induced surface reconstruction. Hydrogen adsorption on a W(100) surface causes a switching transition in the symmetry of the displacements of the W atoms within the ordered c(2x2) phase. This transition is modeled by an effective Hamiltonian, where the hydrogen degrees of freedom are integrated out. Based on extensive Monte Carlo renormalisation group calculations we show that the switching transition is of second order at high temperatures and of first order at low temperatures. This behavior is qualitatively explained in terms of an XY model where there is an interplay between four and eight fold anisotropy fields. We also compare the calculated phase diagrams with a simple mean field theory.Comment: CSC Preprint, 31 pages (plain TeX file, no figures

Lymphatic filariasis control in Tanga Region, Tanzania:status after eight rounds of mass drug administration

BackgroundLymphatic filariasis (LF) control started in Tanga Region of Tanzania in 2004, with annual ivermectin/albendazole mass drug administration (MDA). Since then, the current project has monitored the effect in communities and schools in rural areas of Tanga District. In 2013, after 8 rounds of MDA, spot check surveys were added in the other 7 districts of Tanga Region, to assess the regional LF status.MethodsLF vector and transmission surveillance, and human cross sectional surveys in communities and schools, continued in Tanga District as previously reported. In each of the other 7 districts, 2¿3 spot check sites were selected and about 200 schoolchildren were examined for circulating filarial antigens (CFA). At 1¿2 of the sites in each district, additional about 200 community volunteers were examined for CFA and chronic LF disease, and the CFA positives were re-examined for microfilariae (mf).ResultsThe downward trend in LF transmission and human infection previously reported for Tanga District continued, with prevalences after MDA 8 reaching 15.5% and 3.5% for CFA and mf in communities (decrease by 75.5% and 89.6% from baseline) and 2.3% for CFA in schoolchildren (decrease by 90.9% from baseline). Surprisingly, the prevalence of chronic LF morbidity after MDA 8 was less than half of baseline records. No infective vector mosquitoes were detected after MDA 7. Spot checks in the other districts after MDA 8 showed relatively high LF burdens in the coastal districts. LF burdens gradually decreased when moving to districts further inland and with higher altitudes.ConclusionLF was still widespread in many parts of Tanga Region after MDA 8, in particular in the coastal areas. This calls for intensified control, which should include increased MDA treatment coverage, strengthening of bed net usage, and more male focus in LF health information dissemination. The low LF burdens observed in some inland districts suggest that MDA in these could be stepped down to provide more resources for upscale of control in the coastal areas. Monitoring should continue to guide the programme to ensure that the current major achievements will ultimately lead to successful LF elimination

Schistosomiasis transmission at high altitude crater lakes in Western Uganda

<p>Abstract</p> <p>Background</p> <p>Contrary to previous reports which indicated no transmission of schistosomiasis at altitude >1,400 m above sea level in Uganda, in this study it has been established that schistosomiasis transmission can take place at an altitude range of 1487–1682 m above sea level in western Uganda.</p> <p>Methods</p> <p>An epidemiological survey of intestinal schistosomiasis was carried out in school children staying around 13 high altitude crater lakes in Western Uganda. Stool samples were collected and then processed with the Kato-Katz technique using 42 mg templates. Thereafter schistosome eggs were counted under a microscope and eggs per gram (epg) of stool calculated. A semi-structured questionnaire was used to obtain demographic data and information on risk factors.</p> <p>Results</p> <p>36.7% of the pupils studied used crater lakes as the main source of domestic water and the crater lakes studied were at altitude ranging from 1487–1682 m above sea level. 84.6% of the crater lakes studied were infective with over 50% of the users infected.</p> <p>The overall prevalence of <it>Schistosoma mansoni </it>infection was 27.8% (103/370) with stool egg load ranging from 24–6048 per gram of stool. 84.3%( 312) had light infections (<100 eggs/gm of stool), 10.8%( 40) had moderate infections (100–400 eggs/gm of stool) and 4.9% (18) had heavy infections (>400 egg/gm of stool). Prevalence was highest in the age group 12–14 years (49.5%) and geometric mean intensity was highest in the age group 9–11 years (238 epg). The prevalence and geometric mean intensity of infection among girls was lower (26%; 290 epg) compared to that of boys (29.6%; 463 epg) (t = 4.383, p < 0.05). Though 61%(225) of the pupils interviewed were aware of the existence of the disease, 78% (290)didn't know the mode of transmission and only 8% (30) of those found infected were aware of their infection status. In a multivariate logistic regression model, altitude and water source (crater lakes) were significantly associated with infection.</p> <p>Conclusion and recommendations</p> <p>The altitudinal threshold for <it>S. mansoni </it>transmission in Uganda has changed and use of crater water at an altitude higher than 1,400 m above sea level poses a risk of acquiring <it>S. mansoni </it>infection in western Uganda. However, further research is required to establish whether the observed altitudinal threshold change is as a result of climate change or other factors. It is also necessary to establish the impact this could have on the epidemiology of schistosomiasis and other vector-borne diseases in Uganda. In addition, sensitisation and mass treatment of the affected community is urgently required.</p

Will all scientists working on snails and the diseases they transmit please stand up?

Copyright © 2012 Adema et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.No abstract available