Search results for "lake"
showing 10 items of 369 documents
The genomic sequence of Exiguobacterium chiriqhucha str. N139 reveals a species that thrives in cold waters and extreme environmental conditions
2017
We report the genome sequence of Exiguobacterium chiriqhucha str. N139, isolated from a high-altitude Andean lake. Comparative genomic analyses of the Exiguobacterium genomes available suggest that our strain belongs to the same species as the previously reported E. pavilionensis str. RW-2 and Exiguobacterium str. GIC 31. We describe this species and propose the chiriqhucha name to group them. ‘Chiri qhucha’ in Quechua means ‘cold lake’, which is a common origin of these three cosmopolitan Exiguobacteria. The 2,952,588-bp E. chiriqhucha str. N139 genome contains one chromosome and three megaplasmids. The genome analysis of the Andean strain suggests the presence of enzymes that confer E. ch…
Photochemical mineralization of terrigenous DOC to dissolved inorganic carbon in ocean
2018
When terrigenous dissolved organic carbon (tDOC) rich in chromophoric dissolved organic matter (tCDOM) enters the ocean, solar radiation mineralizes it partially into dissolved inorganic carbon (DIC). This study addresses the amount and the rates of DIC photoproduction from tDOC and the area of ocean required to photomineralize tDOC. We collected water samples from 10 major rivers, mixed them with artificial seawater, and irradiated them with simulated solar radiation to measure DIC photoproduction and the photobleaching of tCDOM. The linear relationship between DIC photoproduction and tCDOM photobleaching was used to estimate the amount of photoproduced DIC from the tCDOM fluxes of the stu…
Isometric embeddings of snowflakes into finite-dimensional Banach spaces
2016
We consider a general notion of snowflake of a metric space by composing the distance by a nontrivial concave function. We prove that a snowflake of a metric space $X$ isometrically embeds into some finite-dimensional normed space if and only if $X$ is finite. In the case of power functions we give a uniform bound on the cardinality of $X$ depending only on the power exponent and the dimension of the vector space.
Fitoplancton de dos lagunas de los humedalesde Xeresa y Xeraco (Valencia, España).
2001
M.Jose.Villena@uv.es Susana.Romo@uv.es Se ha estudiado la composición fitoplanctónica de dos lagunas costeras mediterráneas, que corresponden a los marjales de Xeresa y Xeraco (Valencia). Estas zonas húmedas de la Comunidad Valenciana poseen un importante valor ecológico y botánico para nuestra Península, aunque actualmente se encuentran amenazadas por transformaciones de tipo turístico o agrícola. Las lagunas estudiadas se caracterizan por ser someras (Zmax: 3 m), oligohalinas, de aguas transparentes y mesotróficas, y por encontrarse sobre lechos de turba y con praderas de macrófitos sumergidos. El fitoplancton observado destaca por presentar una composición similar para ambas lagunas, con…
Efficacité interne de l'enseignement primaire aux pays de la Communauté Economique des Pays des Grands Lacs (CEPGL) : question approfondie sur le Rwa…
2011
This PhD study has been achieved with objective to carry out the level of internal efficiency of the primary education in the CEPGL countries and the progress reaches toward the education for all after the period of ethnic and armed conflicts. In addition, specifically for Rwanda, to underline the individual, families and school factors explanatory of the repetition and drop-out in the primary schools. The data of our analysis come from different reports of ministries, international organizations and publications of researchers. The analysis of the primary education inside CEPGL countries, by the indicators that document education supply and demand, show that, after the period of conflicts,…
Bacterial community response to changes in a tri-trophic cascade during a whole-lake fish manipulation
2015
Microbial communities play a key role in biogeochemical processes by degrading organic material and recycling nutrients, but can also be important food sources for upper trophic levels. Trophic cascades might modify microbial communities either directly via grazing or indirectly by inducing changes in other biotic or in abiotic factors (e.g., nutrients). We studied the effects of a tri-trophic cascade on microbial communities during a whole-lake manipulation in which European perch (Perca fluviatilis) were added to a naturally fishless lake divided experimentally into two basins. We measured environmental parameters (oxygen, temperature, and nutrients) and zooplankton biomass and studied th…
Corneal thickness differences between sexes after oxybuprocaine eye drops.
2014
PURPOSE We aimed to analyze the corneal thickness (CT) values of female and male subjects before and after instillation of oxybuprocaine 0.4% anesthetic eye drops. METHODS The CT of 30 female subjects and 28 male subjects was measured using scanning-slit corneal topography (Orbscan Topography System II, Orbscan, Inc, Salt Lake City, UT). Measurements were carried out before and 3 minutes after the instillation of oxybuprocaine 0.4% eye drops. RESULTS The difference between the baseline values and those obtained after anesthesia ranged as follows: male subjects: central, -26 to +24 μm; superior, -24 to +23 μm; inferior, -19 to +20 μm; nasal, -25 to +30 μm; and temporal, -21 to +20 μm; female…
Anatomic study of the corneal thickness of young emmetropic subjects.
2004
PURPOSE To study the corneal thickness of young emmetropic subjects. METHODS One thousand eyes of 1000 young healthy emmetropic subjects were analyzed with the Orbscan Topography System II (Orbscan, Inc, Salt Lake City, UT) from January 2001 to May 2003. The age of the subjects ranged from 20 to 30 years old (mean +/- SD = 27.12 +/- 2.86). The mean of 5 consecutive measurements of the corneal thickness in the center of the cornea and at temporal, superotemporal, inferotemporal, nasal, inferonasal, and superonasal cornea were recorded. RESULTS The corneal thickness at the following areas ranged as follows: 518 to 589 microm center; 603 to 678 microm nasal; 620 to 689 microm superonasal; 600 …
Quantitative anatomical differences in central corneal thickness values determined with scanning-slit corneal topography and noncontact specular micr…
2005
PURPOSE This study was designed to analyze the differences in central corneal thickness values determined with noncontact specular microscopy and scanning-slit corneal topography. The measurements were performed on the same eye. METHODS We analyzed the central corneal thickness values of 93 patients (n = 93) by means of noncontact specular microscopy (Topcon SP-2000P noncontact specular microscope, Topcon Corp., Tokyo, Japan) and scanning-slit corneal topography (Orbscan Topography System II, Orbscan Inc., Salt Lake City, UT). One experienced physician performed 3 consecutive central corneal thickness measurements with both devices. RESULTS The central corneal thickness values obtained by m…
Geochemical processes assessed by Rare Earth Elements fractionation at "Laguna Verde" acidic-sulphate crater lake (Azufral volcano, Colombia)
2017
Abstract The geochemical behaviour of major elements, Fe, Al, Mn, and Rare Earth Elements (REE) was investigated in the “Laguna Verde” acidic crater lake of Azufral volcano (Colombia). The cold lake water (T close to 10 °C) is sulphate-dominated, due to absorption and oxidation of H2S (pH 2.1–2.7, Eh 196–260 mV), and Na-enriched (Total Dissolved Solids 0.79 g L−1). The total amount of REE dissolved in the lake ranges from 3.3 to 9.1 ppb. The REE patterns normalized to the local rocks show a Light Rare Earth Elements (LREE) depletion quite constant in the 15 samples. Similar patterns were already found in the acidic sulphate springs of Nevado del Ruiz volcano-hydrothermal system, caused by t…