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Ovarian cancer (OC) represents a serious health problem worldwide. In Mexico, most OC patients are detected at late stages, consequently making OC one of the leading causes of death in women after reaching puberty. Personalized medicine (PM) provides an individualized therapeutic opportunity for treating each patient relying on “omic” tools to match the correct drug with the specific pathogenic genomic signature. PM can help predict the best therapeutic option for each affected woman suffering from OC. In recent years, Mexico has made contributions to the PM of OC; however, it still has a long way to go for its full implementation in the country’s health system. World J Oncol. 2021;12(4):85-92 doi: https://doi.org/10.14740/wjon1383

Objective: To investigate factors associated with cognitive impairment (CI) in institutionalized Mexican older adults. Material and methods: Cross-sectional study of residents of three long-term care facilities in the metropolitan area of Monterrey, Mexico. A medical history, Mini-Mental State Examination (MMSE), Barthel index, geriatric depression scale, and a nutritional screening were performed. CI was defined as MMSE ≤24. Results: Of 280 octogenarian residents (72.1% females) 61.1 % had a MMSE ≤24. Older age (OR=1.047), functional dependence (OR=10.309), malnutrition (OR=2.202), urinary incontinence (OR=2.588), and history of fracture (OR=1.764) were directly associated to CI. While higher education level (OR=0.583) and the use of antihypertensives (OR=0.521), antihistamines (OR=0.322), antiprostatic hypertrophy (OR=0.219), and lipid-lowering drugs (OR=0.575) were inversely associated. Conclusions: The evaluation of cognitive performance and its associated factors is essential for institutionalized patients in order to implement a management program aimed at reducing the progression of CI and its possible complications.

The Matsigenka people living traditional lifestyles in remote areas of the Amazon rely on a fish-based diet that exposes them to methylmercury (MeHg) at levels that have been associated with decreased IQ scores. In this study, the association between Hg levels and working memory was explored using the framework of the Multicomponent Model. Working memory tasks were modified to fit the culture and language of the Matsigenka when needed and included measures for verbal storage (Word Span) visuospatial storage (Corsi Block Task) and a measure of executive functions, the Self-Ordered Pointing Task (SOPT). An innovation of the Trail Making Tests A & B (TMT A & B) was pilot tested as another potential measure of executive functions. The mean hair Hg levels of 30 participants, ages 12 to 55 years, from three different communities (Maizal, Cacaotal and Yomibato) was 7.0 ppm (sd = 2.40), well above the World Health Organization (WHO) limit for hair of 2.0 ppm and ranged from 1.8 to 14.2 ppm, with 98% of a broader sample of 152 individuals exceeding the WHO limit. Hair Hg levels showed significant associations with cognitive performance, but the degree varied in magnitude according to the type of task. Hg levels were negatively associated with executive functioning performance (SOPT errors), while Hg levels and years of education predicted visuospatial performance (Corsi Block accuracy). Education was the only predictor of Word Span accuracy. The results show that Hg exposure is negatively associated with working memory performance when there is an increased reliance on executive functioning. Based on our findings and the review of the experimental research, we suggest that the SOPT and the Corsi Block have the potential to be alternatives to general intelligence tests when studying remote groups with extensive cultural differences.

Artisanal and small-scale gold mining (ASGM) is the primary global source of anthropogenic mercury (Hg) emissions and a large source of landscape change. ASGM occurs throughout the world, including in the Peruvian Amazon. This data set contains measurements of surface water, precipitation, throughfall, leaves, sediment, soil, and air samples from across the Madre de Dios region of Peru, in locations near and remote from ASGM. These data were collected to determine the fate and transport of Hg across the landscape. Samples were collected in 2018 and 2019. Data predominantly included total Hg and methyl Hg concentrations in surface water, precipitation, throughfall, leaves, sediment, soil, and air. Additional water and soil parameters were also measured to better characterize their chemistry. There are no copyright restrictions; please cite this data paper when the data are used in publication.

Humid tropical forests play a dominant role in the functioning of Earth but are under increasing threat from changes in land use and climate. How forest vulnerability varies across space and time and what level of stress forests can tolerate before facing a tipping point are poorly understood. Here, we develop a tropical forest vulnerability index (TFVI) to detect and evaluate the vulnerability of global tropical forests to threats across space and time. We show that climate change together with land-use change have slowed the recovery rate of forest carbon cycling. Temporal autocorrelation, as an indicator of this slow recovery, increases substantially for above-ground biomass, gross primary production, and evapotranspiration when climate stress reaches a critical level. Forests in the Americas exhibit extensive vulnerability to these stressors, while in Africa, forests show relative resilience to climate, and in Asia reveal more vulnerability to land use and fragmentation. TFVI can systematically track the response of tropical forests to multiple stressors and provide early-warning signals for regions undergoing critical transitions.

Artificial lake expansion and high mercury loading synergistically increase mercury contamination risk from gold mining., Artisanal and small-scale gold mining (ASGM) is the largest global source of anthropogenic mercury emissions. However, little is known about how effectively mercury released from ASGM is converted into the bioavailable form of methylmercury in ASGM-altered landscapes. Through examination of ASGM-impacted river basins in Peru, we show that lake area in heavily mined watersheds has increased by 670% between 1985 and 2018 and that lakes in this area convert mercury into methylmercury at net rates five to seven times greater than rivers. These results suggest that synergistic increases in lake area and mercury loading associated with ASGM are substantially increasing exposure risk for people and wildlife. Similarly, marked increases in lake area in other ASGM hot spots suggest that “hydroscape” (hydrological landscape) alteration is an important and previously unrecognized component of mercury risk from ASGM.

Introduction Human Mesenchymal Stem Cells (hMSCs) are multipotent stem cells capable of renewing themselves and differentiation in vitro into different kinds of tissues. In vivo hMSCs are sources of trophic factors modulating the immune system and inducing intrinsic stem cells to repair damaged tissues. Currently, there are multiple clinical trials (CT) using hMSCs for therapeutic purposes in a large number of clinical settings. Material and Methods The search strategy on clinicaltrials.gov has focused on the key term “Mesenchymal Stem Cells”, and the inclusion and exclusion criteria were separated into two stages. Stage 1, CT on phases 1–4: location, the field of application, phase, and status. For stage 2, CT that have published outcome results: field of application, treatment, intervention model, source, preparation methods, and results. Results By July 2020, there were a total of 1,138 registered CT. Most studies belong to either phase 2 (61.0%) or phase 1 (30.8%); most of them focused in the fields of traumatology, neurology, cardiology, and immunology. Only 18 clinical trials had published results: the most common source of isolation was bone marrow; the treatment varied from 1–200 M hMSCs; all of them have similar preparation methods; all of them have positive results with no serious adverse effects. Conclusions There appears to be a broad potential for the clinical use of hMSCs with no reported serious adverse events. There are many trials in progress, their future results will help to explore the therapeutic potential of these promising cellular sources of medicinal signals.

Both invasive mesopredators and altered fire regimes impact populations of vulnerable native species. Understanding how these forces interact is critical for designing better conservation measures for endangered species. This study draws on Indigenous ecological knowledge and practice to explore heterogeneity in faunal responses to Indigenously managed landscapes in the Western Desert of Australia. Using track plot surveys and satellite image analysis of fire histories, we find evidence that pyrodiversity increases activity measures of dingoes and monitor lizards. Dingoes were more active in recently burnt patches, while foxes were more active in slightly older burnt patches. These results add to previous work showing significant effects of pyrodiversity on kangaroo populations in the region. Together, the findings suggest that Aboriginal burning not only creates diverse niches for native animals, it helps to facilitate the ecological role of species that are themselves functionally vital. This work adds to a growing body of research suggesting that the loss of Aboriginal burning can cascade through ecosystems by transforming and simplifying ecological networks, thus contributing to the decline and extinction of vulnerable species.

Chronic liver diseases account for a considerable toll of incapacities, suffering, deaths, and resources of the nation's health systems. They can be prevented, treated or even cured when the diagnosis is made on time. Traditional liver biopsy remains the gold standard to diagnose liver diseases, but it has several limitations. Liquid biopsy is emerging as a superior alternative to surgical biopsy given that it surpasses the limitations: it is more convenient, readily and repeatedly accessible, safe, cheap, and provides a more detailed molecular and cellular representation of the individual patient's disease. Progress in understanding the molecular and cellular bases of diseased tissues and organs that normally release cells and cellular components into the bloodstream is catapulting liquid biopsy as a source of biomarkers for diagnosis, prognosis, and prediction of therapeutic response, thus supporting the realization of the promises of precision medicine. The review aims to summarize the evidence of the usefulness of liquid biopsy in liver diseases, including the presence of different biomarkers as circulating epithelial cells, cell-free nucleic acids, specific species of DNA and RNA, and the content of extracellular vesicles.

Gold shops in artisanal and small-scale gold mining communities represent major point sources of airborne mercury pollution. Concentrations of elemental mercury (Hg0) emitted by these shops can be determined using a portable atomic absorbance spectrometer (AAS) with Zeeman correction. These measured Hg0 concentrations can then be correlated to position as determined by a hand-held GPS unit, and the resulting data mapped using a Geographic Information System (GIS). A detailed method for obtaining and analyzing data collected near gold shops in Mazuko, Peru is provided. Maps generated using this method were employed to identify point sources of Hg0 contamination originating from gold shops in ASGM communities and were shared with local city managers to assist in urban planning.•A detailed method is provided to collect and process data, ultimately generating a map that allows for the screening of a community to identify point sources of Hg0 contamination.•Raw data is provided, as well as a video detailing data processing and mapping using a common spreadsheet program and an open-source GIS.•The generated map can be used for determining areas where people may be exposed to elevated Hg0 concentrations and/or occupational mercury vapor exposure, targeted enforcement, or outreach to limit Hg0 pollution., Graphical abstract Image, graphical abstract

Recent studies from the Madre de Dios region of Peru report elevated mercury exposure among the general population. Our objective was to assess mercury exposure, risk factors, risk perceptions, and knowledge among women of childbearing age, a population of concern due to risks to infant and fetal health. We collected hair samples and administered a survey among 200 women aged 18-49 years residing in Madre de Dios. Hair total mercury (THg) concentrations were analyzed in accordance with EPA Method 7473. Associations between exposures and potential risk factors were analyzed using generalized linear mixed models. Geometric mean hair THg concentration (±standard deviation) for all participants was 1.62 ± 2.54 μg/g (range: 0.01-30.12 μg/g), and 67 participants (33.5%) had concentrations above the 2.2 μg/g reference dose established by the World Health Organization (WHO). Higher exposure was significantly associated with higher fish consumption (p = 0.03) and less mercury knowledge (p 0.0001), but not with age or educational attainment. Most participants (86.2%) expressed concern about mercury contamination, but few (26.2%) had knowledge of the health risks associated with exposure. Many residents consumed fish species previously found to have low mercury concentrations, but more than 25% of participants reported consuming fish species with high mercury concentrations. We did not observe cross-sectional differences in fish intake among women who were pregnant or breastfeeding at the time of data collection.

Gold mining is the largest source of mercury (Hg) pollution worldwide. The discharge of mercury in the environment bears direct human health risks and is likely to increase cascading effects throughout local food chains. In the Peruvian Amazon the mining process consists of slashing and burning trees, followed by extraction of gold-bearing sediment, amalgamation with Hg and gold recovery, leading each year to the degradation of 6,000-10,000 ha and the release of 180 metric tons of Hg per year to the enviroment. The purpose of this study was to determine soil Hg levels in soils of abandoned alluvial gold mine spoils and undisturbed forest in the Madre de Dios region, the epicenter of alluvial gold mining in Peru. We selected gold mine spoils of the two most important technologies locally applied for gold extraction, i.e., Minimally Mechanized Mining (MMM) and Highly Mechanized Mining (HMM), in the native communities of Laberinto and Kotzimba, respectively. We collected 127 and 35 soil samples (0-20cm depth) from potentially contaminated sites and undisturbed forest, respectively. Physicochemical analysis and determination of Hg levels were determined for all soil samples. None of the samples had Hg concentrations above Peruvian, Canadian and British Environmental Quality Standards for Agricultural Soil (6.6mg/kg). Hg levels in MMM and HMM were not significantly different between the two areas. The main variables explaining variation of soil Hg concentrations were the vegetation cover, soil organic matter, soil pH and clay particle content, which explained up to 80% of data set variation. Surprisingly, highest Hg concentrations were found in untouched old-growth forest bordering the mine spoils, but there was also a trend of increasing Hg concentrations with the regenerating vegetation. Our findings suggest that Hg concentrations in old mine spoils are low and shouldn’t stand in the way of efforts to restore soil conditions and develop sustainable land uses. However, it is urgent to end the use of Hg in mining operation to decrease human and environmental risks.

Artisanal gold mining in Amazon forests and rivers has been reported in all Amazonian countries. Amazon mining has a wide range of negative effects and severe environmental and social consequences. Given that the activity in the region is mostly illegal, there are few studies published in the scientific literature on recovery of areas degraded by gold mining. This study conducts an experimental reforestation project aimed to evaluate soil degradation and explore the seedling survivorship and early growth of 51 tropical tree species in gold mined areas at 5 study sites distributed across the Madre de Dios region, in the Peruvian Amazon. The study evaluates the effect of biochar amendments on the survivorship and growth of 51 tropical species. The study also analyzes the influence of species wood density on seedling performance one year after planting. In order to inform further restoration plantation strategies, species were chosen with the end goals of timber production, biodiversity enhancement, and soil restoration. Site degradation, soil properties and mercury levels were analyzed in degraded areas and paired reference forest patches. Soils after gold mining are found to be highly degraded, with soil C being nearly absent, cation content greatly decreased, and loss of fine sediment. Soil mercury levels were found below national and international environmental quality standards. A positive correlation and a statistically significant relationship were found between survivorship and wood density. This reveals that the higher the wood density of the species, the higher the survival percentage. Growth and overall performance of mid, and especially low wood density species were significantly increased by biochar additions, while no effect was recorded on high wood density species growth. The study provides guidance on the post-ASGM restoration potential for 51 common and useful tree species and gives practitioners recommendations for combinations of species and fertilization treatments to optimize restoration designs.

The complex dimension of the space of linearly full almost complex 2-spheres of area 4 π d 4\pi d in the round 6-sphere is calculated to be d + 8 d+8 . Explicit examples of these objects are constructed for every integer value of the degree, d ≥ 6 d\ge 6 , d ≠ 7 d\ne 7 . Furthermore, it is shown that when d = 6 d=6 this space is isomorphic to the group G 2 ( C ) G_2({\mathbb C}) , and when d = 7 d=7 this space is empty. We also show that the dimension of the space of nonlinearly full almost complex 2-spheres of area 4 π d 4\pi d in the round 6-sphere is 2 d + 5 2d+5 .

Research Highlights: We find that biochar plus fertilizer has synergistic and positive effects on seedling growth and robustness, but slightly lowers early seedling survival. Biochar plus fertilizer has the potential to greatly decrease costs associated with afforestation as compared to traditional fertilization and gives better results. Background and Objectives: Biochar can improve soil fertility and plant yield in crops. However, there is little information regarding the effects of biochar on trees, even though reforestation/afforestation projects are increasing and are often unsuccessful due to soil fertility limitations. This study aims to increase knowledge of biochar use as a reforestation tool. Materials and Methods: We measured survival and growth in an early ((Guazuma crinita Mart. [n = 240])) and a late (Terminalia amazonia (J.F. Gmel.) Exell. [n = 240]) successional species under 6 different biochar treatments in a 6-month nursery experiment. Results: (i) Survival was highest in the 1 t/ha biochar treatment, while treatments containing fertilizers or biochar at 5 t/ha lowered the survival rate of both species compared to the control, (ii) simultaneous addition of biochar and fertilizer lead to significant increases in height, diameter, total number of leaves, and aboveground and belowground biomass of both species as compared to other treatments, (iii) biochar treatment containing 1 t/ha with and without fertilizer showed significantly better results than applications of 5 t/ha, and (iv) Guazuma crinita responded more strongly to treatments containing biochar and fertilizers compared to Terminalia amazonia, which is suggestive of greater synergetic effects of biochar and fertilizer addition on early successional tree species. Conclusions: Applying biochar and fertilizer is synergistic and outperforms any single treatment, as well as the control, in terms of plant performance. This case study suggests that biochar can greatly improve reforestation/afforestation projects by increasing plant performance while substantially reducing fertilizer and labor maintenance costs. Field experiments and testing of additional species is needed to generalize the findings.

Brazil has the largest commercial beef cattle herd in the world, with cattle ranching being particularly prominent in the 200-million ha, Brazilian neotropical moist savanna biome, known as Cerrado, one of the world’s hotspots for biodiversity conservation. As decreasing productivity is a major concern affecting the Cerrado pasturelands, evaluation of pasture conditions through the determination of biophysical parameters is instrumental for more effective management practices and herd occupation strategies. Within this context, the primary goal of this study was the regional assessment of pasture biophysical properties, through the scaling of wet- and dry-season ground truth data (total biomass, green biomass, and % green cover) via the combined use of high (Landsat-TM) and moderate (MODIS) spatial resolution vegetation index images. Based on the high correlation found between NDVI (normalized difference vegetation index) and % green cover (r = 0.95), monthly MODIS-based % green cover images were derived for the 2009–2010 hydrological cycle, which were able to capture major regional patterns and differences in pasture biophysical responses, including the increasing greenness values towards the southern portions of the biome, due to both local conditions (e.g., more fertile soils) and management practices. These results corroborate the development of biophysically-based landscape degradation indices, in support of improved land use governance and natural area conservation in the Cerrado.

Cultivated pastures are the dominant land-use unit in Brazil, with the cattle raising sector representing ∼50% of the total Brazilian emissions of greenhouse gases. About 44% of the Brazilian cattle herd is located in the 204 million ha Cerrado, the Brazilian savanna biome and one of the world's hotspots for conservation, where pasture is still the major driving force behind the ongoing land clearance. In the face of the environmental challenges posed by the Cerrado cultivated pastures, 50% of which are estimated to be already severely degraded and where most of the pasture-related fires in Brazil occur, in this study we report the findings on the use of key Moderate Resolution Imaging Spectroradiometer MODIS Land MODLAND products for retrieving biophysical patterns and trends of cultivated pastures over the entire Brazilian savanna biome. The areas of Cerrado covered by cultivated pastures were analysed by the following 2008 MODIS products: MOD13Q1 enhanced vegetation index, MOD11A2 land-surface temperature, MOD15A2 leaf area index, and MCD45A1 fire-affected areas. Specifically, 23 MOD13Q1 composites for the whole year of 2008 were used as a net primary productivity proxy. Our results indicate the ability of moderate resolution orbital imagery to consistently depict the main characteristics and regional variation in the biophysical properties of the Cerrado pastures, which clearly depend on management practices, usage, and environmental conditions. In particular, these results corroborate the feasibility of an operational MODIS-based monitoring system providing early fire warnings and overall quality assessments in support of a more efficient and sustainable herd occupation and more appropriate land-use destination.

We prove the conjecture, posed in 1993 by Bolton and Woodward, that the dimension of the space of harmonic maps from the 2-sphere to the 2nsphere is 2d + n 2 . We also give an explicit algebraic method to construct all harmonic maps from the 2-sphere to the m-sphere.

An important debate in the literature on exurban sprawl is whether low-density development results from residential demand, as operationalized by developers, or from exclusionary zoning policies. Central to this debate is the purpose of zoning, which could alternatively be a mechanism to increase the utility of residents by separating land uses and reducing spillover effects of development, or an obstacle to market mechanisms that would otherwise allow the realization of residential preferences. To shed light on this debate, we developed an agent-based model of land-use change to study how the combined effects of zoning-enforcement levels, density preferences, preference heterogeneity, and negative externalities from development affect exurban development and the utility of residents. Our computational experiments show that sprawl is not inevitable, even when most of the population prefers low densities. The presence of negative externalities consistently encourage sprawl while decreasing average utility and flattening the utility distribution. Zoning can reduce sprawl by concentrating development in specific areas, but in doing so decreases average utility and increases inequality. Zoning does not internalize externalities; instead, it contains externalities in areas of different development density so that residents bear the burden of the external effects of the density they prefer. Effects vary with residential preference distributions and levels of zoning enforcement. These initial investigations can help inform policy makers about the conditions under which zoning enforcement is preferable to free-market development and vice versa. Future work will focus on the environmental impacts of different settlement patterns and the role land-use and market-based policies play in this relationship.

Using the twistorial approach and some previous results, we prove the conjecture that the dimension of the moduli space of harmonic maps of area $4 \pi d$ from the 2-sphere to the $2n$ -sphere is $2 d+n^2$ for the particular case $n=3$ .

Powerful computational tools are becoming available to represent the behavior of complex systems. Agent-based modeling, in particular, facilitates an examination of the system-level outcomes of the heterogeneous actions of a set of heterogeneous agents: for example, patterns of land-use and land-cover change, such as urban sprawl as a result of residential location decisions. These new tools create new demands for data, and empirical studies of the selection behavior of residents. Using resident responses from the 2001 Detroit Area Study survey, we compared two alternative approaches to characterizing the heterogeneous preferences of agents; both based on a factor analysis of resident responses to questions about their reasons for moving to their current location. We used cluster analysis to identify how many and what types of residents there are, grouped by similar preferences. We also evaluated the relationships between socioeconomic and demographic characteristics and location preferences using regression trees, and evaluated the fit of the relationship to determine the degree to which socioeconomic characteristics predict preferences. The results showed that the preferences of resident exurbans of single-family homes in the Detroit metropolitan area were heterogeneous and that distinct preference groups do exist in resident populations, but are not well characterized on the basis of simple socioeconomic and demographic variables. We conclude that, given the heterogeneous nature of preferences and a relatively limited number of preference groupings observed in the survey respondents, agent-based models simulating resident behavior should reflect this diversity in the population and incorporate distinct agent classes of empirically derived preference distributions.

Using a birational correspondence between the twistor space ofS2nand projective space, we describe, up to birational equivalence, the moduli space of superminimal surfaces inS2nof degreedas curves of degreedin projective space satisfying a certain differential system. Using this approach, we show that the moduli space of linearly full maps is nonempty for sufficiently large degree and we show that the dimension of this moduli space forn=3and genus0is greater than or equal to2d+9. We also give a direct, simple proof of the connectedness of the moduli space of superminimal surfaces inS2nof degreed.

The influence of deforestation on tropical watersheds has received limited study. We compared seven catchments in the Venezuelan Andes to examine variation in the relative extent of forested versus dis- turbed land and the potential consequences of changing land use on river ecosystems. These watersheds formed a northeast (Rio Acarigua) to southwest (Rio Bumbun) transect and exhibited a gradient in readily observable human settlement and disturbance. Overall, forest cover increased and agriculture and pasture land decreased from the Acarigua to the Bumbun. Human building density and road density showed a paral- lel trend. Catchments varied in intrinsic characteristics as well. Catchments to the northeast originated at lower elevations and had wider, flatter valleys in the lowest piedmont zone, compared with rivers to the southwest. All seven catchments had broadly similar forest cover at approximately 50-60% within the lowest (200-800 m) el- evation zone, but they exhibited a strong gradient in the amount of forested versus disturbed land in zones at 800-1400 m and 1400-2600 m. Although the number of buildings was greatest in the 200- to 800-m zone, build- ing density was greater in the 800- to 1400-m zone for the more disturbed catchments, possibly reflecting the areas suitable for coffee production. Land-use change within these catchments is likely to alter hydrology, sediment trans- port, and habitat conditions within river systems, with adverse consequences for aquatic biodiversity.

Objective To describe the characteristics of children less than three years of age with medically intractable epilepsy, who underwent Vagus Nerve Stimulator (VNS) therapy at Children's Hospital of Pittsburgh between 2004 and 2011. Methods: Retrospective chart review. Results: Seventeen patients were identified; adequate follow-up was available for 15. Median follow up duration was 4.3 years (1.4–10.2 years). 12/15 (80%) had a known etiology for their epilepsy. All patients had more than 1 seizure per week prior to VNS and a history of status epilepticus was frequent (40%, 6/15). Five patients (33%) reported improved seizure frequency at one year after VNS. A normal MRI was associated with seizure improvement ( p =0.007). No patient had status epilepticus after VNS at one-year follow-up. At three years after VNS, four patients had experienced status epilepticus with only one patient experiencing multiple episodes. Complications were seen in 2/15 (13%) patients and in 2/21 (9.5%) procedures. Significance: A normal MRI was associated with seizure improvement at one year in children less than three years of age at the time of VNS implant. The degree of overall seizure reduction was modest, but the frequency of status epilepticus was decreased after VNS implant. VNS was tolerated well in this age group.

A set of quantitative analytical data from the alluvial aquifer of the Pisuerga river, located at the north-east of Valladolid (Spain), has been processed by multivariate statistical techniques in order to investigate the evolution of the groundwater composition between two surveys. The original matrix consisted of 16 physico-chemical variables, determined in 32 groundwater samples collected in 32 sampling sites of the aquifer. The surveys were carried out in October 1994, at the end of the irrigation and low water period just before autumn rains, and in April–May 1995 at the beginning of the irrigation and high water period and after the recharge of aquifer. The experimental 64×16 matrix was analysed by Principal Component Analysis (PCA), and the resulting Principal Components (PCs) and Varimax rotated PCs (VFs) analysed by means of box and bivariate plots. The exploration of the correlation matrix allowed to uncover strong associations between some variables (sulphate, chloride, hydrogencarbonate, sodium, potassium, magnesium, calcium and electrical conductivity) as well as a lack of association between the others (pH, nitrate, and trace metals). PCA showed the existence of up to five significant PCs which account for 71.39% of the variance. Two of them can be initially assigned to ‘mineralization’ whereas the other PCs are built from variables indicative of pollution. Box and bivariate plots of the two first PCs showed that ‘mineralization’ is maintained through surveys and that trace elements increase from the first to the second survey in all zones, as a possible consequence of soil leaching caused by the rise of the groundwater level. Varimax rotation allowed to ‘break up’ the ‘mineralization’ PC into two VFs, assigned respectively to ‘natural’ mineralization and to ‘saline’ man-made contamination (sodium and chloride). Box and bivariate plots of VFs confirmed the existence of a differential ‘natural’ mineralization pattern, now ascribed exclusively to dissolution of geological materials, as well as the presence of a zone with unusually high levels of ‘saline’ contamination attributed to leakages from sanitary systems. The plot of VFs also allowed to visualise seasonal variations, identifying a process of dilution of the ‘natural’ mineralization during the recharge of the aquifer, and an increase of the ‘saline’ contamination, assigned to a variety of non-natural causes.

21 physico-chemical parameters have been determined in 47 groundwater samples collected in October 1994 from the alluvial aquifer of the Pisuerga river, located at the north-east of Valladolid (north-western Spain). Conventional hydrochemical methods and multivariate statistical analysis have been used to discriminate natural phenomena and pollution processes in the area. It has been demonstrated the existence of a heterogeneity in groundwater mineral contents related to anthropic actions such as irrigation, source of irrigation water and location of polluting sources. This study demonstrates the existence of two sub-units in the alluvial aquifer (left and right river banks) with different hydrochemical characteristics, and identifies three different singular areas in the left bank. Groundwater from this bank showed higher levels of dissolved ions caused by concentration processes derived from the predominant use of groundwater for crop irrigation, whilst in the right bank of the aquifer less saline water from canals is used. Degradation of groundwater quality has been observed in some areas of the left aquifer sub-unit (north, Santovenia and south-central sites) where anomalous high concentrations of sulphate, sodium, chloride and nitrate were measured, and can be related to the presence of potentially polluting sources such as leachates from industrial waste disposals, sewage effluents and use of organic and inorganic fertilizers.

Mytilan, isolated from the mantle of the mussel Crenomytilus grayanus and which possesses high immunomodulating activity, is a non-covalently linked complex of a polysaccharide (95%) and protein (5%) with lectin activities. Chromatography of mytilan on agarose separated the polysaccharide and protein constituents. The protein appeared to have the lectin properties. Methylation analysis, Smith degradation, digestion with alpha-amylase, and 13C-n.m.r. spectroscopy showed the polysaccharide to be a glycogen-like α- d -glucan.

We determine explicitly the normalized potential, a Weierstrass-type representation, of a superconformal surface in an even-dimensional sphere S2n in terms of certain normal curvatures of the surface. When the Hopf differential is zero the potential embodies a system of first order equations governing the directrix curve of a superminimal surface in the twistor space of the sphere. We construct a birational map from the twistor space of S2n into ℂPn(n+1)/2. In general, birational geometry does not preserve the degree of an algebraic curve. However, we prove that the birational map preserves the degree, up to a factor 2, of the twistor lift of a superminimal surface in S6 as long as the surface does not pass through the north pole. Our approach, which is algebro-geometric in nature, accounts in a rather simple way for the aforementioned first order equations, and as a consequence for the particularly interesting class of superminimal almost complex curves in S6. It also yields, in a constructive way, that a generic superminimal surface in S6 is not almost complex and can achieve, by the above degree property, arbitrarily large area.

The effects of task complexity and vicarious reward upon children's ability to learn a substantive educational task through modeling were investigated. After observing a model's performance, all Ss were offered direct reward for matching responses. Accuracy of imitative learning was inversely related to task complexity and facilitated by the presence of vicarious reward. However, as predicted, vicarious reward had a significant effect only for Ss in the high-complexity condition, tended to enhance the performance of Ss in the moderate-complexity condition, and had negligible effects for Ss exposed to the low-complexity task. These results are consistent with the hypothesis that vicarious and direct reward may operate additively, with the former serving primarily to enhance Ss' attention to the relevant modeling cues.

As in an earlier study with older children, a brief exposure to a model was shown to produce appreciable learning by preschool Ss on a substantive educational task. Although vicarious reward again favorably influenced imitative learning under high-complexity conditions, the borderline reliability of this effect with younger Ss suggests that the effects of vicarious reward should be studied developmentally.

This study investigated the effects of verbally ascribing the social characteristic of “friendlessness” to a film-mediated model upon children’s acquisition and imitation of his modeled commodity preferences and also attempted to determine whether the combination of this verbal description and symbolic modeling of altruism would enhance prosocial behavior in the form of donations to the model. Significant imitation effects were found for both the “neutral” and “friendless” model groups when compared with a control group. Prosocial behavior was enhanced by the “friendless” model, and all modeling groups showed almost perfect acquisition of the model’s preferences.