ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1432-0975
    Keywords: Key words Infragravity waves ; Tides ; Surface slopes ; Caribbean ; Wave set-up
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract A two-week study, at Tague Reef, St. Croix, USVI investigated the magnitude and spatial variation of tides, sea level differences, infragravity waves, and unidirectional cross-reef currents on a modern coral reef. Infragravity oscillations of water level (∼ 27 min period) of 1–2 cm height correlate with a quarter wavelength resonance over the shelf. Particle displacements associated with these waves may be important to the dispersive characteristics of the reef environment. Estimates of cross-reef mass transport per unit width ranged from 0.058 to 0.032 m2s -1. Sea level differences across the reef (1–4 cm) varied at diurnal and infragravity periods with contributions from wave set-up, and a small contribution from cross-shelf wind stress to the observed sea level differences. The quadratic bottom friction coefficient over the reef was estimated at 0.06–0.2, 20–70 times greater than on open shelves, reflecting the reef’s extreme bottom roughness.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    International journal of salt lake research 7 (1998), S. 87-108 
    ISSN: 1573-8590
    Keywords: benthos ; crater lakes ; littoral ; macroinvertebrates ; Mexico ; Puebla ; saline lakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract Two saline crater lakes in the basin of Oriental, Puebla-Tlaxcala-Veracruz, were investigated for littoral benthic macroinvertebrates. Fifty taxa were identified with the oligochaetes, amphipods, chironomids and leeches the dominant organisms. These four taxa made up to 99 per cent in both number and biomass. Limnodrilus hoffmeisteri, Hyalella azteca, Tanypus (Apelopia) sp. and Stictochironomus sp. were the most abundant organisms. Unlike other saline lakes which have a littoral benthos dominated by chironomids, Alchichica and Atexcac were dominated by oligochaetes (70–73 per cent). The gastropod, Physa sp., was found up to a salinity of 8 g L-1; in other studies, it has been found in lower salinities. L. hoffmeisteri is also a typical inhabitant of freshwater lakes, particularly of deep waters. It was dominant in the shallow, saline waters of the two lakes studied. Salinity did not affect species richness. Alchichica, the most saline of the six crater lakes of Puebla (salinity, 7.4 g L-1), had 30 per cent more species than the freshwater lakes, and double the species number of Atexcac. It seems the main factor controlling species richness and the density and biomass of organisms in Alchichica and Atexcac is the presence of aquatic vegetation. It does this by increasing habitat heterogeneity and providing food and protection against predators.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    International journal of salt lake research 7 (1998), S. 87-108 
    ISSN: 1573-8590
    Keywords: benthos ; crater lakes ; littoral ; macroinvertebrates ; Mexico ; Puebla ; saline lakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract Two saline crater lakes in the basin of Oriental, Puebla-Tlaxcala-Veracruz, were investigated for littoral benthic macroinvertebrates. Fifty taxa were identified with the oligochaetes, amphipods, chironomids and leeches the dominant organisms. These four taxa made up to 99 per cent in both number and biomass.Limnodrilus hoffmeisteri, Hyalella azteca, Tanypus (Apelopia) sp. andStictochironomus sp. were the most abundant organisms. Unlike other saline lakes which have a littoral benthos dominated by chironomids, Alchichica and Atexcac were dominated by oligochaetes (70–73 per cent). The gastropod,Physa sp., was found up to a salinity of 8 g L−1; in other studies, it has been found in lower salinities.L. hoffmeisteri is also a typical inhabitant of freshwater lakes, particularly of deep waters. It was dominant in the shallow, saline waters of the two lakes studied. Salinity did not affect species richness. Alchichica, the most saline of the six crater lakes of Puebla (salinity, 7.4 g L−1), had 30 per cent more species than the freshwater lakes, and double the species number of Atexcac. It seems the main factor controlling species richness and the density and biomass of organisms in Alchichica and Atexcac is the presence of aquatic vegetation. It does this by increasing habitat heterogeneity and providing food and protection against predators.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Transport in porous media 31 (1998), S. 89-108 
    ISSN: 1573-1634
    Keywords: nonlinear conductivity ; volume averaging ; closure problem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract The assumption of constant local coefficients is one of the first restrictions in most of the smoothing theories for transport in porous media. In this paper we present a formal analysis of the effects produced by nonconstant local transport coefficients on the nonlinear behavior of the effective transport properties. In particular, we use the volume averaging method to study heat transport in a two-component system considering the local thermal conductivities as analytical functions of the temperature. Within this approach we obtain a general expression for the effective nonlinear thermal conductivity dependence on the averaged temperature gradient. The important result is that the effective conductivity is obtained by a linearly bounded problem (the closure problem), just as if the conductivities were constants, by replacing the constant conductivities by the actual temperature dependent ones. As an example, we model the porous medium as cylindrical inclusions in a periodic array and solve the closure problem for the case of the one-equation model. We analyze the values of the second derivative of the thermal conductivity with respect to the temperature to establish the range where the nonlinear corrections must be considered to correctly describe the effective transport.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1435-0629
    Keywords: Key words: disturbance; ecosystem management; land use; recovery; spatial heterogeneity; succession.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: ABSTRACT Large, infrequent disturbances (LIDs) can have significant impacts yet seldom are included in management plans. Although this neglect may stem from relative unfamiliarity with a kind of event that rarely occurs in the experience or jurisdiction of individual managers, it may also reflect the assumption that LIDs are so large and powerful as to be beyond the ability of managers to affect. However, some LIDs can be affected by management, and for many of those that cannot be affected, the resilience or recovery of the system disrupted by the disturbance can be influenced to meet management goals. Such results can be achieved through advanced planning that allows for LIDs, whether caused by natural events, human activities, or a combination of the two. Management plans for LIDs may adopt a variety of goals, depending on the nature of the system and the nature of the anticipated disturbance regime. Managers can choose to influence (a) the system prior to the disturbance, (b) the disturbance itself, (c) the system after the disturbance, or (d) the recovery process. Prior to the disturbance, the system can be managed in ways that alter its vulnerability or change how it will respond to a disturbance. The disturbance can be managed through no action, preventive measures, or manipulations that can affect the intensity or frequency of the disturbance. Recovery efforts can focus on either managing the state of the system immediately after the disturbance or managing the ongoing process of recovery. This review of the management implications of LIDs suggests that management actions should be tailored to particular disturbance characteristics and management goals. Management actions should foster survival of residuals and spatial heterogeneity that promote the desired recovery pattern and process. Most importantly, however, management plans need to recognize LIDs and include the potential for such disturbances to occur.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1435-0157
    Keywords: Key words Contamination ; hydrochemistry ; karst ; Mexico ; water supply
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Résumé Les eaux de cinq cénotés, qui sont normalement utilisées pour des activités de plein air, dans la région touristique de Cancun–Tulum (Mexique), ont été soumises à analyses chimiques pour savoir si les cénotés peuvent être considérés comme des sources d'eau potable. Plusieurs paramètres dépassent les normes mexicaines en matière d'eau potable; mais comme ceux-ci ne posent pas de problème réel de santé, quatre des cinq cénotés peuvent être captés pour l'eau potable. Les contaminants habituels dans les eaux de la presqu'île du Yucatan, coliformes fécaux et concentrations élevées en nitrate, sont la plupart du temps au-dessous des normes (respectivement 0 à 460 germes/100 ml et 0,31 à 1,18 mg/l). Bien que ces quatre cénotés satisfassent aux normes, il est nécessaire de mettre en place des règles précises de l'utilisation de l'eau souterraine, afin d'éviter la contamination par les germes fécaux et par les nitrates, ainsi que l'intrusion marine.
    Abstract: Resumen Se analizó hidroquímica y bacteriológicamente el agua de algunos cenotes localizados a lo largo del corredor turístico Cancun–Tulum, que actualmente se utilizan para diversas actividades recreativas, para determinar su potencial de uso como fuente de abastecimiento de agua potable. La mayor parte de los parámetros excedieron los criterios establecidos en la Norma Mexicana para Agua Potable (NMAP), sin embargo, como éstas no representan una riesgo para la salud, el agua de cuatro de los cinco cenotes puede ser emplada como fuente de abastecimiento de agua potable. Los contaminantes comúnes del agua subterránea de la península de Yucatán, coliformes fecales y nitratos, se encuentran en la mayoría de los casos por debajo de la NMAP (0–460 NMP/ 100 ml y 0.31–1.18 mg/l, respectivamente). A pesar de que estos cuatro cenotes cumplen con la NMAP, es necesario desarrollar una política de manejo adecuada del agua subterránea para evitar la contaminación de este recurso (fecal y por nitratos), así como la intrusión de agua salina.
    Notes: Abstract  Waters from five cenotes that are currently being used for aquatic recreational activities and that lie along the Cancun–Tulum touristic corridor, Mexico, were evaluated hydrochemically to determine whether the cenotes may be considered as potential drinking-water sources. Several parameters exceed the Mexican Drinking Water Standards (MDWS), but since they do not pose a significant health threat, four of the five cenotes may be used as drinking-water sources. The common contaminants in the Yucatan Peninsula, fecal coliforms and nitrate, are in most cases below the MDWS (0–460 MPN/100 ml and 0.31–1.18 mg/L, respectively). Although these four cenotes meet the MDWS, a careful groundwater management policy needs to be developed to avoid contamination (fecal and nitrates) and salt-water intrusion.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 381 (1998), S. 1-7 
    ISSN: 1573-5117
    Keywords: Tropical limnology ; meromixis ; nutrients ; plankton ; Nayarit ; Mexico ; Isabela island
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Isabela Crater-Lake is a bright-green, hypersaline lake (68–112.5 mS cm-1) on Isabela Island off the Pacific coast of Nayarit, Mexico. Some salient features were documented in November 1993. It appears meromictic, with three well-defined strata separated by sharp pycnoclines. Surface water was warm (32 °C) reaching a subsurface (0.5–1 m) maximum temperature (33 °C), declining gradually to 26.7 °C at maximum depth (17.5 m). Dissolved oxygen was near saturation at the surface, attained 145 percent saturation at 0.5 m, but was completely absent by 2.5 m. Eh was maximum at the surface (123 mV), declining to a minimum at 3 m (–261 mV), and was about –240 mV from 3.5 m to the bottom. The pH varied from 9.3 in surface waters to slightly acid (6.4) in deep anoxic layers. Atypically, NO3 was more abundant than NH4 in both aerobic and anaerobic strata. PO4 and SiO2 concentrations were extremely high. The planktonic microbial community was formed by four groups: bacteria (photosynthetic sulfur bacteria and heterotrophic bacteria), phytoflagellates (mainly cryptomonads), heterotrophic nanoflagellates ( Spumella spp., Bodo spp.) and ciliates (Hypotricha and Oligotricha). Bacteria occurred throughout the water column, but other biota were restricted to surface waters.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1573-5117
    Keywords: aufwuchs ; polyurethane foam units ; colonization ; saline lakes ; crater lakes ; Mexico
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Littoral protozoan assemblages from two hyposaline crater-lakes (Lakes Alchichica and Atexcac) located in the Oriental Valley, center of Mexico, were studied using the polyurethane foam units (PFU) colonization method. Fifteen PFU (5 dates, three replicates per date, 64 × 72 × 50 mm) were located in the littoral area of each lake and collected at 8, 14, 20–21, 28–29 and 38–39 d intervals. Both lakes were hyposaline (Salinity between 6 and 7.1 g l-1) and alkaline (pH range: 8.4–9.1). Eighty seven species were observed in both lakes. In Alchichica 44 species and 43 in Atexcac. Ciliates and flagellates species dominated the assemblages' composition. The flagellates Bodo caudatus and Spumella termo and the ciliate Cyclidium glaucoma were the most abundant species in Alchichica, while in Atexcac the flagellates Cryptomonas ovata and B. caudatus and the ciliates C. glaucoma and Stylonychia notophora were most abundant. Except for S. notophora, which consumes algae, the other species are mainly bactivores.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Publication Date: 1998-08-04
    Description: Gross genetic lesions of chromosome 10 occur in 30–50% of sporadic human melanomas. To test the functional significance of this observation, we have developed anin vitroloss of heterozygosity approach in which a wild-type chromosome 10 was transferred into melanoma cells, where there was selection for its breakage and regional deletion to relieve its growth suppressive effects. The overlap of these events was at band 10q23, the site of the recently isolatedPTEN/MMAC1tumor suppressor gene, suggesting it as a potential target. Although the gene was expressed in the parental cells, both of its chromosomal alleles contained truncating mutations.In vitroloss of heterozygosity resulted in loss of the chromosomally introduced wild-typePTEN/MMAC1, and ectopic expression of the gene caused cell growth suppression. Thus, this approach identifiedPTEN/MMAC1as a target in malignant melanoma and may provide an alternative means to localizing tumor suppressor genes.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Publication Date: 1998-08-17
    Print ISSN: 1431-2174
    Electronic ISSN: 1435-0157
    Topics: Geosciences
    Published by Springer
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...