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A Simultaneous X-ray Diffraction-Differential Scanning Calorimetry Study into the Phase Transitions of Mefenamic Acid
In this study, the polymorphic transitions of mefenamic acid (MA) were studied by synchrotron X-ray powder diffraction combined with differential scanning calorimetry (XRD-DSC). The initial material was found to be phase-pure form I which, when heated, produces two endotherms that can be observed by DSC at 162.72 and 219.55°C. The former was found to correspond to a solid–solid enantiotropic transition from form I to a mixture of forms II and III. The latter is the melting point of form II. As form I is heated, significantly greater unit-cell expansion is seen in the a direction than in b and c, which can be explained by the stronger intermolecular interactions in the bc plane. Refinements of the reported MA structures against the patterns collected during heating revealed that at 175°C there exists a mixture of forms I, II and III, whereas only forms II and III remain at 205°C. However, reflections are observed at both temperatures which cannot be fitted with the known forms of MA. It is hypothesized that a new form of MA is produced upon heating. The stability of MA after the enantiotropic transition temperature is II > III > I, which differs from the previously reported II > I > III
Reproducibility of species recognition in modern planktonic foraminifera and its implications for analyses of community structure
Applications of planktonic foraminifera in Quaternary palaeoceanographic and
palaeobiological studies require consistency in species identification. Yet
the degree of taxonomic consistency among the practitioners and the effects
of any potential deviations on community structure metrics have never been
quantitatively assessed. Here we present the results of an experiment in
taxonomic consistency involving 21 researchers representing a range of
experience and taxonomic schools from around the world. Participants were
asked to identify the same two sets of 300 specimens from a modern
subtropical North Atlantic sample, one sieved at > 125 µm
and one at > 150 µm. The identification was carried out
either on actual specimens (slide test) or their digital images
(digital test). The specimens were fixed so the identifications could be
directly compared. In all tests, only between one-quarter and one-eighth of
the specimens achieved absolute agreement. Therefore, the identifications
across the participants were used to determine a consensus ID for each
specimen. Since no strict consensus ( > 50 % agreement) could be
achieved for 20–30 % of the specimens, we used a soft consensus based
on the most common identification. The average percentage agreement relative
to the consensus of the slide test was 77 % in the > 150 µm
and 69 % in the > 125 µm test. These values
were 7 % lower for the digital analyses. We find that taxonomic
consistency is enhanced when researchers have been trained within a taxonomic
school and when they regularly perform community analyses. There is an almost
negligible effect of taxonomic inconsistency on sea surface temperature
estimates based on transfer function conversion of the census counts,
indicating the temperature signal in foraminiferal assemblages is correctly
represented even if only two-thirds of the assemblage is consistently
identified. The same does not apply to measures of diversity and community
structure within the assemblage, and here we advise caution in using compound
datasets for such studies. The decrease in the level of consistency when
specimens are identified from digital images is significant and
species-specific, with implications for the development of training sets for
automated identification systems.</p
Infección por Theileria annae en un perro esplenectomizado
La babesiosis canina es una enfermedad infecciosa de distribución mundial debida a la proliferación en los hematíes del perro de unas babesias específicas transmitidas por garrapatas. Si bien ha sido tradicionalmente asumido que las únicas especies que causan enfermedad en la especie canina son Babesia canis y Babesia gibsoni, publicaciones recientes demuestran que una tercera especie (Theileria annae) también puede causar una enfermedad muy severa. Este trabajo presenta el segundo caso publicado de esta forma de Theileria annae en un perro de 14 años, de raza Basset Hound, esplenectomizado cinco meses antes, que se presentó en la clínica veterinaria con signos de hipertermia, hemoglobinuria, temblores y apatía. El estudio de laboratorio constató una acusada anemia hemolítica regenerativa y una intensa trombocitopenia como datos más característicos. En la extensión de sangre periférica se visualizaron múltiples merozoítos intra (22%) y extraeritrocitarios de pequeño tamaño (1-2 micras), forma anular y presentación única en la mayoría de hematíes. La prontitud del diagnóstico y del tratamiento específico con dipropionato de imidocarb hizo que el cuadro clínico evolucionase con rapidez hacia la curación, en contra de lo que es habitual en los animales esplenectomizados.
Babesia microti-like en un perro inmunocompetente
La babesiosis canina es una enfermedad infecciosa de distribución mundial causada por parásitos intraeritrocitarios transmitidos por garrapatas. Si bien ha sido tradicionalmente asumido que sólo dos de las 73 especies de babesias identificadas causan enfermedad en la especie canina, Babesia canis y Babesia gibsoni, recientes publicaciones demuestran que una tercera especie (Babesia microti-like) también puede parasitar a perros. Este último parásito, genéticamente relacionado con Babesia microti, es el origen de una enfermedad endémica entre la población canina del noroeste de España. Este trabajo presenta un caso no experimental de esta forma de Babesia microti-like en un perro cocker spaniel de 9 años, sin antecedentes de inmunodeficiencia ni de esplenectomía, que se presenta en la clínica veterinaria con signos de hipertermia, hemoglobinuria, escalofríos y apatía. Una muy intensa parasitemia (24%), junto con trombopenia y una acusada anemia hemolítica regenerativa fueron los hallazgos más caractéristicos. En la extensión de sangre periférica se visualizaron múltiples merozoitos intraeritrocitarios (parasitemia de un 24%) de pequeño tamaño (1-2 um) y presentación única en cada hematíe. Cuarenta y ocho horas después del comienzo de los síntomas, y tras tratamiento específico con dipropionato de imidocarb el perro evolucionó hacia la curación
Dynamical Friction in dE Globular Cluster Systems
The dynamical friction timescale for globular clusters to sink to the center
of a dwarf elliptical galaxy (dE) is significantly less than a Hubble time if
the halos have King-model or isothermal profiles and the globular clusters
formed with the same radial density profile as the underlying stellar
population. We examine the summed radial distribution of the entire globular
cluster systems and the bright globular cluster candidates in 51 Virgo and
Fornax Cluster dEs for evidence of dynamical friction processes. We find that
the summed distribution of the entire globular cluster population closely
follows the exponential profile of the underlying stellar population. However,
there is a deficit of bright clusters within the central regions of dEs
(excluding the nuclei), perhaps due to the orbital decay of these massive
clusters into the dE cores. We also predict the magnitude of each dE's nucleus
assuming the nuclei form via dynamical friction. The observed trend of
decreasing nuclear luminosity with decreasing dE luminosity is much stronger
than predicted if the nuclei formed via simple dynamical friction processes. We
find that the bright dE nuclei could have been formed from the merger of
orbitally decayed massive clusters, but the faint nuclei are several magnitudes
fainter than expected. These faint nuclei are found primarily in M_V > -14 dEs
which have high globular cluster specific frequencies and extended globular
cluster systems. In these galaxies, supernovae-driven winds, high central dark
matter densities, extended dark matter halos, the formation of new star
clusters, or tidal interactions may act to prevent dynamical friction from
collapsing the entire globular cluster population into a single bright nucleus.Comment: 15 pages, 2 tables, 7 figures; to appear in the Astrophysical
Journal, April 20, 200
Changes in rod and frame test scores recorded in schoolchildren during development--a longitudinal study.
The Rod and Frame Test has been used to assess the degree to which subjects rely on the visual frame of reference to perceive vertical (visual field dependence-independence perceptual style). Early investigations found children exhibited a wide range of alignment errors, which reduced as they matured. These studies used a mechanical Rod and Frame system, and presented only mean values of grouped data. The current study also considered changes in individual performance. Changes in rod alignment accuracy in 419 school children were measured using a computer-based Rod and Frame test. Each child was tested at school Grade 2 and retested in Grades 4 and 6. The results confirmed that children displayed a wide range of alignment errors, which decreased with age but did not reach the expected adult values. Although most children showed a decrease in frame dependency over the 4 years of the study, almost 20% had increased alignment errors suggesting that they were becoming more frame-dependent. Plots of individual variation (SD) against mean error allowed the sample to be divided into 4 groups; the majority with small errors and SDs; a group with small SDs, but alignments clustering around the frame angle of 18°; a group showing large errors in the opposite direction to the frame tilt; and a small number with large SDs whose alignment appeared to be random. The errors in the last 3 groups could largely be explained by alignment of the rod to different aspects of the frame. At corresponding ages females exhibited larger alignment errors than males although this did not reach statistical significance. This study confirms that children rely more heavily on the visual frame of reference for processing spatial orientation cues. Most become less frame-dependent as they mature, but there are considerable individual differences
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