bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantifying the effects of aggregation, particle size and components on the colour of Mediterranean soils
Authors: SÁnchez‐Marañón M. , Soriano M. , Melgosa M. , Delgado G. , Delgado R. 
Published: August 2004

SummaryAggregation, particle size, and chemical composition affect the colour of the soil. We have attempted to quantify and understand these effects in 12 Mediterranean soils. We measured the CIELAB colour variableshab,L*, andC*abin aggregated and dispersed soil samples, and also in coarse sand, fine sand, silt, and clay samples before and after sequential removal of organic matter, carbonates, and Fe oxides. Grassmann's colour‐mixing equations adjusted by regression analysis described the colour of the dispersed soil from its particle‐size fractions with an error of 1% forhab, 4% forL*, and 9% forC*ab. This suggests that the contribution of each fraction to the colour of the dispersed soil can be accurately calculated by its colorimetric data weighted by its content and a regression coefficient, which was greatest for clay. We inferred the influence of a component within each fraction by measuring the colour changes after its removal. Iron oxides reducedhabof the silicated substrate by 19%, reducedL* by 12%, and increasedC*abby 64% in all particle‐size fractions. Carbonates and organic matter had little influence: the former because they impart little colour to the silicates and the latter because there was little of it. The CIELAB colour‐difference between dispersed and aggregated soil (mean ΔE*ab = 15.3) was due mainly to ΔL* (−14.7). Aggregation contributed to diminishingL* of dispersed soil by 34%. Scanning electron microscopy showed that Fe oxides and organic coatings cover the surface of aggregates thereby influencing soil colour.
Water repellency of volcanic ash soils from Ecuadorian páramo: effect of water content and characteristics of hydrophobic organic matter
Authors: Poulenard J. , Michel J.C. , Bartoli F. , Portal J.M. , Podwojewski P. 
Published: August 2004

SummaryWater repellency of volcanic ash soils from the Ecuadorian páramo was studied by a combination of extraction and analysis of water‐repellent products, Molarity Ethanol Droplet values, water contact‐angle measurements by capillary rise, and N2 adsorption isotherms. The undried samples studied are hydrophilic, but exhibit water repellency after moderate drying (48 hours at 30°C). The advancing water contact‐angle measured by capillary rise varies from 78° to 89°. These water contact‐angles decrease strongly after extraction of organic materials by an isopropanol–water mixture. Elemental analysis, infrared spectra and gas chromatography‐mass spectrometry analyses were used to characterize the extracts. The results show that long‐chain fatty acids and more complex non‐polar alkyl components (waxes) are the main water‐repellent materials. The deposition of such extracted materials onto hydrophilic sand leads to the rapid increase of water contact‐angle until values close to those measured on the soil samples are achieved. Assuming a coating of the mineral surface by organic hydrophobic products and using Cassie's law, the water contact‐angle of extracted materials was computed. The values ranged from 100° to 157°. Nitrogen specific surface areas of the soils studied were very small, indicating a low adsorbent–adsorbate interaction on hydrophobic surfaces. These results partially validate the hypothesis of water‐repellent materials that occur as coatings at least after a drying process.
Analysing spatially intermittent variation of nitrous oxide emissions from soil with wavelets and the implications for sampling
Authors: Lark R. M. , Milne A. E. , Addiscott T. M. , Goulding K. W. T. , Webster C. P. , O'Flaherty S. 
Published: August 2004

SummaryEmissions of gases from the soil are known to vary spatially in a complex way. In this paper we show how such data can be analysed with the wavelet transform. We analysed data on rates of N2O emission from soil cores collected at 4‐m intervals on a 1024‐m transect across arable land at Silsoe in England. We used a thresholding procedure to represent intermittent variation in N2O emission from the soil as a sparse wavelet process, i.e. one in which most of the wavelet coefficients are not significantly different from zero. This analysis made clear that the rate of N2O emission varied more intermittently on this transect than did soil pH, for which many more of the wavelet coefficients had to be retained. This account of intermittent variation motivated us to consider a class of random functions, which we call wavelet random functions, for the simulation of spatially intermittent variation. A wavelet random function (WRF) is an inverse wavelet transform of a set of random wavelet coefficients with specified variance at each scale. We generated intermittent variation at a particular scale in the WRF by specifying a binormal process for the wavelet coefficients at this scale. We showed by simulation that adaptive sampling schemes are more efficient than ordinary stratified random sampling to estimate the mean of a spatial variable that is intermittent at a particular scale. This is because the sampling can be concentrated in the more variable regions. When we simulated values that emulate the intermittency of our data on N2O we found that the gains in efficiency from simple adaptive sampling schemes were small. This was because the emission of N2O is intermittent over several disparate scales. More sophisticated adaptive sampling is needed for these conditions, and it should embody knowledge of the relevant soil processes.
Historical review of malarial control in southern African with emphasis on the use of indoor residual house‐spraying
Authors: Mabaso Musawenkosi L. H. , Sharp Brian , Lengeler Christian 
Published: August 2004

SummaryIndoor residual house‐spraying (IRS) mainly with dichlorodiphenyltrichloroethane (DDT) was the principal method by which malaria was eradicated or greatly reduced in many countries in the world between the 1940s and 1960s. In sub‐Saharan Africa early malarial eradication pilot projects also showed that malaria is highly responsive to vector control by IRS but transmission could not be interrupted in the endemic tropical and lowland areas. As a result IRS was not taken to scale in most endemic areas of the continent with the exception of southern Africa and some island countries such as Reunion, Mayotte, Zanzibar, Cape Verde and Sao Tome. In southern Africa large‐scale malarial control operations based on IRS with DDT and benzene hexachloride (BHC) were initiated in a number of countries to varying degrees. The objective of this review was to investigate the malarial situation before and after the introduction of indoor residual insecticide spraying in South Africa, Swaziland, Botswana, Namibia, Zimbabwe and Mozambique using historical malarial data and related information collected from National Malaria Control Programmes, national archives and libraries, as well as academic institutions in the respective countries. Immediately after the inception of IRS with insecticides, dramatic reductions in malaria and its vectors were recorded. Countries that developed National Malaria Control Programmes during this phase and had built up human and organizational resources made significant advances towards malarial control. Malaria was reduced from hyper‐ to meso‐endemicity and from meso‐ to hypo‐endemicity and in certain instances to complete eradication. Data are presented on the effectiveness of IRS as a malarial control tool in six southern African countries. Recent trends in and challenges to malarial control in the region are also discussed.
Human African trypanosomiasis amongst urban residents in Kinshasa: a case‐control study
Authors: Robays J. , Ebeja Kadima A. , Lutumba P. , Miaka mia Bilenge C. , Kande Betu Ku Mesu V. , De Deken R. , Makabuza J. , Deguerry M. , Van der Stuyft P. , Boelaert M. 
Published: August 2004

SummaryBackground  Increasing numbers of human African trypanosomiasis (HAT) cases have been reported in urban residents of Kinshasa, Democratic Republic Congo since 1996. We set up a case‐control study to identify risk factors for the disease.Methods  All residents of the urban part of Kinshasa with parasitologically confirmed HAT and presenting for treatment to the city's specialized HAT clinics between 1 August, 2002 and 28 February, 2003 were included as cases. We defined the urban part as the area with contiguous habitation and a population density >5000 inhabitants per square kilometre. A digital map of the area was drawn based on a satellite image. For each case, two serologically negative controls were selected, matched on age, sex and neighbourhood. Logistic regression models were fitted to control for confounding.Results  The following risk factors were independently associated with HAT: travel, commerce and cultivating fields in Bandundu, and commerce and cultivating fields in the rural part of Kinshasa. No association with activities in the city itself was found.Discussion  In 2002, the emergence of HAT in urban residents of Kinshasa appears mainly linked to disease transmission in Bandundu and rural Kinshasa. We recommend to intensify control of these foci, to target HAT screening in urban residents to people with contact with these foci, to increase awareness of HAT amongst health workers in the urban health structures and to strengthen disease surveillance.
Migrants’ risky sexual behaviours in India and at home in far western Nepal
Authors: Poudel Krishna C. , Jimba Masamine , Okumura Junko , Joshi Anand B. , Wakai Susumu 
Published: August 2004

SummaryObjective  To examine Nepali migrants’ vulnerability to HIV/sexually transmitted infections (STIs) and their possible role in causing the epidemic in far western Nepal.Methods  From August to October 2000, we conducted six focus group discussions among 53 returned migrants from India, mainly from Mumbai. Data were analysed by interpretative thematic analysis.Results  Migrants commonly had multiple sexual encounters, changed partners, and used condoms infrequently both in India and at home. Several factors influenced them to practice high‐risk sexual behaviours. In India, these included peer norms and pressures, cheaper sex, lack of family restraint, drinking alcohol, and low perceived vulnerability to HIV/STIs. In Nepal, these factors included the migrants’ new status, frequent local festivals, and low perceived vulnerability to HIV/STIs. Participants displayed substantial deficits in their knowledge of HIV/STIs.Conclusions  This study revealed Nepali migrants’ high‐risk sexual behaviours both abroad and at home. Understanding these realities will assist in the development of culturally appropriate HIV/STI interventions necessary to halt the spread of HIV/STIs in Nepal.
Weekly iron supplements given by teachers sustain the haemoglobin concentration of schoolchildren in the Philippines
Authors: Roschnik Natalie , Parawan Amado , Baylon Melba Andrea B. , Chua Teresita , Hall Andrew 
Published: August 2004

SummaryObjectives  To examine the effectiveness of weekly iron supplements given for 10 weeks by teachers to children in rural schools in the Philippines.Methods  Forty‐nine rural primary schools took part in the study and were randomly assigned to two groups: children in 25 schools received a weekly tablet providing 108 mg iron while children in 24 schools acted as controls. All children were dewormed before the start of the iron supplementation. The haemoglobin concentration of a systematic sample of one in three children in two classes in each school was estimated before and 5–17 weeks after the end of the iron supplementation.Results  A total of 1510 children aged 7–12 years were studied at both surveys. The mean haemoglobin concentration of children in the intervention group did not change significantly; in the untreated group it fell by 3.8 g/l and the prevalence of anaemia rose from 14.3% to 25.6%. The difference between study groups was significantly larger amongst the younger children (7–8 years), and was observed in both anaemic and non‐anaemic children.Conclusion  Even where anaemia is only a mild public health problem, weekly iron supplements given by teachers may prevent a fall in the haemoglobin concentration, and can benefit both anaemic and non‐anaemic children.
Toxoplasma gondiispreading in an urban area evaluated by seroprevalence in free‐living cats and dogs
Authors: Meireles L. R. , Galisteo A. J. , Pompeu E. , Andrade H. F. 
Published: August 2004

SummaryInfection by the protozoan parasite,Toxoplasma gondiiis widely prevalent in humans and animals throughout the world. Transmission takes place mainly by ingestion of raw or undercooked meat that contains parasite cysts or by ingestion of oocysts excreted in cat faeces, which can contaminate water and raw vegetables. The incidence of toxoplasmosis in urban areas can thus be also related to environmental contamination with oocysts. A direct measure of this environmental contamination by oocyst counting is unfeasible for technical reasons. An interesting alternative for measuringT. gondiiurban spreading is the seroprevalence in free‐living urban animals, used as sentinels, once they are exposed to similar risks ofToxoplasmainfection‐like humans. With this aim, we tested serum samples from stray cats and dogs for antibodies toT. gondiiby indirect haemagglutination assay (IHA) and enzyme‐linked immunosorbent assay (ELISA). Antibodies toT. gondiiwere found in 40% (40 of 100) of the cats, less than the 50.5% (101 of 200) found in dogs by ELISA (P < 0.05). Haemagglutination showed low resolution and concordance, precluding their use for diagnosis ofT. gondiiinfection compared with ELISA. The prevalence ofT. gondiiwas lower among stray cats probably due to their selective alimentary habits and lower water and food intake.Toxoplasma gondiiseroprevalence in stray dogs and cats could be an indirect indicator of the parasite spreading in urban areas.
Infant schistosomiasis in Ghana: a survey in an irrigation community
Authors: Bosompem K. M. , Bentum Irene A. , Otchere J. , Anyan W. K. , Brown C. A. , Osada Y. , Takeo S. , Kojima S. , Ohta N. 
Published: August 2004

SummaryWe used a rapid, visually read, field applicable monoclonal antibody (MoAb)‐dipstick assay for specific diagnosis of urinary schistosomiasis together with microscopy to determine the prevalence of infant schistosomiasis in a community in the Awutu‐Efutu Senya District in the Central Region of Ghana. The study group consisted of 97 infants (51 males and 46 females) aged 2 months to 5 years. A total of 75 of 97 (77.3%) subjects submitted stool samples; none had Schistosoma mansoni. Three individuals (3.1%) had hookworms but there were no other intestinal helminths. The urinary schistosomiasis prevalence by MoAb‐dipstick (30%) was higher (P < 0.05) than that estimated by microscopy (11.2%). However, three of nine (33.3%) microscopically confirmed cases tested MoAb‐dipstick positive after pre‐treatment of the urine specimen with heat. The youngest infant to be found infected with S. haematobium microscopically was 4 months old. Fifteen of 71 S. haematobium egg negative individuals tested dipstick positive, giving a dipstick specificity of 78.9% as compared with microscopy as gold standard test. The relative sensitivity of the dipstick was 100%.
Viewpoint: Why and how tuberculosis control should be included in health sector reviews
Authors: Schreuder Bert , Visschedijk Jan , Gondrie Peter , Van Cleeff Maarten 
Published: August 2004

SummarySector‐wide approaches (SWAps) are currently implemented in several, predominantly highly donor‐dependent low‐income countries, particularly in Sub‐Saharan Africa. SWAp intends to enhance health sector performance, especially efficiency, effectiveness, coherence and sustainability. SWAps have been criticized for not being able to produce tangible results and the credibility of a SWAp would increase substantially if such results in terms of health services outputs could be demonstrated. We argue that the monitoring of tuberculosis within the SWAp reviews held to assess sector performance deserves a higher profile. Tuberculosis constitutes in the first place and one of the major public health problems in most of the countries, where SWAps have been introduced, but provided that the programme is integral part of the sector policy and financial management, the indicators used for monitoring TB control programmes can also be used as excellent proxies for monitoring overall health sector performance.
The PfCRT (K76T) point mutation favours clone multiplicity and disease severity in Plasmodium falciparum infection
Authors: Ranjit M. R. , Das A. , Chhotray G. P. , Das B. P. , Das B. N. , Acharya A. S. 
Published: August 2004

SummaryIn Orissa, a malaria‐hyperendemic area of India, we assessed the relationship between the PfCRT (K76T) point mutation of Plasmodium falciparum and the clinical severity of malaria. Forty uncomplicated and 36 severe malaria cases were selected, and parasite species, density and schizontaemia determined by examination of Giemsa‐stained thick or thin blood films. The PfCRT point mutation was analysed by PCR–RFLP and genotypes of the parasite isolates investigated by nested PCR using the polymorphic region of the merozoite surface protein‐2. We found that (i) the prevalence of the PfCRT point mutation was significantly higher (P < 0.01) in severe malaria cases and that (ii) heavy parasitaemia along with clone multiplicity was statistically more common (P < 0.01) in severe cases. These associations may be due to progression of uncomplicated to severe disease after chloroquine treatment failure and/or increased virulence of chloroquine‐resistant parasites. The implications for antimalarial treatment policy are discussed.
A prospective study of bloodstream infections as cause of fever in Malawi: clinical predictors and implications for management
Authors: Peters Remco P. H. , Zijlstra Ed E. , Schijffelen Maarten J. , Walsh Amanda L. , Joaki George , Kumwenda John J. , Kublin James G. , Molyneux Malcolm E. , Lewis David K. 
Published: August 2004

SummaryObjective  To determine the contribution of a blood culture service to the diagnosis of fever in a resource‐poor setting and to identify clinical predictors of specific bloodstream infections (BSI).Methods  In a descriptive, prospective study at the Medical Wards at Queen Elizabeth Central Hospital, Blantyre, Malawi, we tried to identify a specific cause of fever in febrile patients, comparing the use of routinely available diagnostic methods with the same methods plus blood culture. Clinical predictors of specific BSIs were sought.Results  A total of 352 patients admitted with fever (axillary temperature ≥37.4 °C) or a history of fever within the last 4 days were enrolled. Tuberculosis (TB) was the diagnosis most commonly suspected initially on clinical grounds (28%), followed by lower respiratory tract infection (16%), malaria (12%) and gastroenteritis (5%). Blood cultures were positive in 128 patients (36%); Mycobacterium tuberculosis was the most commonly isolated organism (57 patients). In most cases the diagnosis of TB had already been made using routinely available diagnostic methods, including chest radiography. In all 16 cases of Streptococcus pneumoniae bacteraemia, infection with this agent was clinically suspected, usually on the basis of pulmonary symptoms and signs. In contrast, in 30 of 65 patients (65%) with non‐typhi salmonellae (NTS) bacteraemia, there were no symptoms or signs specifically suggestive of this diagnosis. Fever ≥39 °C and splenomegaly predicted NTS bacteraemia with an odds ratio of 8.4 (95% confidence interval 3.4–20.6, P < 0.001).Conclusion  BSIs are common among patients admitted with fever. While BSI with mycobacteraemia and S. pneumoniae can usually be predicted on clinical grounds and with routinely available diagnostic methods, NTS bacteraemia often presents as a primary BSI without localizing symptoms and signs. Splenomegaly in this population indicates NTS bacteraemia rather than malaria.
Failure to deplete anti‐Galα1‐3Gal antibodies after pig‐to‐baboon organ xenotransplantation by immunoaffinity columns containing multiple Galα1‐3Gal oligosaccharides
Authors: Mañez Rafael , Domenech Nieves , Centeno Alberto , Lopez‐Pelaez Eduardo , Crespo Fabian , Juffe Alberto , Duthaler Rudolf O. , Katopodis Andreas G. 
Published: August 2004

Abstract:  Background:  The impact of anti‐Galα1‐3Gal (αGal) antibodies on the acute humoral xenograft rejection (AHXR) of pig organs transplanted in baboons is unclear.Methods:  Twenty‐three baboons underwent heterotopic pig heart transplantation (Tx). Groups A (n = 5) and B (n = 6) received non‐transgenic and human decay accelerating factor (hDAF) pig hearts, respectively, without any treatment. Groups C (n = 5) and D (n = 7) were transplanted with non‐transgenic and hDAF organs, respectively, and the exclusive treatment was repeated extracorporeal immunoadsorptions (EIA) before and after Tx with an αGal column containing disaccharide (DI), trisaccharide (TRI) 2 and pentasaccharide (PENTA) oligosaccharides.Results:  In group A, 3 of 5 xenografts underwent hyperacute rejection (HAR). No xenograft from groups B, C and D experienced HAR, most of them failing from AHXR. Immediately after Tx and up to day 2, the level of immunoglobulin (Ig)M and IgG anti‐αGal DI, TRI2 and TRI6, and anti‐pig hemolytic antibody (APHA) antibodies decreased in all the groups by 80 to 96% compared with the concentration present before Tx. From day 3 to AHXR, a sustained increase of anti‐αGal IgM DI, TRI2 and TRI6, and APHA occurred in all groups. EIA depleted anti‐αGal IgM and APHA before Tx, but it did not modify the increase of these antibodies after Tx. Baboon serum samples before Tx, pre‐incubated in vitro with 1 mg/ml of DI, TRI2 and TRI6, had an average of 93% reduction of anti‐αGal IgM antibodies specific against each one of these αGal oligosaccharides. In contrast, at AHXR, the average reduction after in vitro pre‐incubation with either 1 or 5 mg/ml of DI, TRI2 and TRI6 was 40%.Conclusions:  The EIA reduces anti‐αGal and APHA antibodies, preventing the HAR of non‐transgenic pig hearts transplanted in baboons, as does hDAF expression. However, EIA does not modify the level of anti‐αGal IgM and APHA antibodies after Tx nor the AHXR of either non‐transgenic or hDAF pig organs. The increase in anti‐αGal IgM after Tx was similar for the different antibodies of the anti‐αGal polymorphism, and was only partially neutralized in vitro with the specific αGal oligosaccharide.