137,191 research outputs found
Melatonin secretion in a strictly subterranean mammal, the Damaraland mole-rat (Cryptomys damarensis)
No full textSubterranean mammals inhabit an environment that is normally devoid of light and are therefore deprived of photoperiodic information that can be used to time important life-history events. An assessment was made of whether melatonin secretion in a strictly subterranean rodent, the Damaraland mole-rat Cryptomys damarensis, can be modified by photoperiod. In experiment 1, a clear diurnal rhythm of melatonin secretion in animals housed under a neutral photoperiod (12L:12D) was observed, with significantly higher melatonin concentrations in the dark compared to the light phase. The same diurnal melatonin rhythm was found 1 day after animals were transferred to either continuous light or continuous dark, suggesting that a circadian rhythm was maintained under acute exposure to light and dark. In experiment 2, melatonin secretion was monitored in a long (14L:10D) and short day (10L:14D) photoperiod and was found to be modified by the photoperiodic change. We therefore suggest that the Damaraland mole-rat possesses a circadian melatonin rhythm that can be physiologically modulated in response to photoperiod
On the dimensionality of the Avogadro constant and the definition of the mole
No full textThere is a common misconception among educators, and even some metrologists, that the Avogadro constant _N_~A~ is (or should be) a pure number, and not a constant of dimension *N*^–1^ (where *N* is the dimension amount of substance). Amount of substance is measured, and has always been measured, as ratios of other physical quantities, and not in terms of a specified pure number of elementary entities. Hence the Avogadro constant has always been defined in terms of the unit of amount of substance, and not vice versa. The proposed redefinition of the mole in terms of a fixed value of the Avogadro constant would cause additional conceptual complexity for no metrological benefit
RNA Sequencing Reveals Differential Expression of Mitochondrial and Oxidation Reduction Genes in the Long-Lived Naked Mole-Rat When Compared to Mice
No full textPubMed ID: 22073188This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Propriedades geotécnicas de compressibilidade de uma argila mole de Itajaí-SC
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Civil, Florianópolis, 2014.No Brasil os depósitos de solos moles estão localizados ao longo de grande parte da região litorânea, incluindo a do Estado de Santa Catarina, onde é freqüente a observação de recalques devido a alta compressibilidade desses solos. Atualmente com o avanço da tecnologia através de pesquisas científicas e a grande ocupação urbana, as áreas de solos compressíveis antes evitadas para implantação de obras vêm sendo utilizadas como alternativas viáveis e se tornando cada vez mais comuns. Dessa forma, esta pesquisa tem como objetivo contribuir com o avanço científico através do conhecimento da estratigrafia do solo local, parâmetros geotécnicos e comportamento do adensamento de um solo mole, localizado no município de Itajaí-SC. No local de estudo é proposta a construção de um aterro visando a proteção contra cheias do Rio Itajaí-Açú, com reforço de geogrelhas e geodrenos para acelerar os recalques. Os parâmetros geotécnicos foram obtidos através de ensaios de campo, com sondagens SPT, CPT, CPTu e DMT, ensaios de laboratório com caracterização, adensamentos convencionais (SIC) e adensamento com deformação controlada (CRS) e também foram estudadas correlações empíricas. Por fim, os parâmetros geotécnicos alcançados foram comparados com outras pesquisas brasileiras. O comportamento do adensamento foi estudado através do cálculo de recalques por adensamento primário, monitoramento de recalques através da instrumentação geotécnica de campo e também por previsões de recalques finais através de aplicação de métodos gráficos. A estratigrafia do solo local é composta por intercalações de camadas de argila e areia, de formação fluvio-marinha e impenetrável após 30m de profundidade. Foram estudadas as duas primeiras camadas de solo mole (Camada A e B), onde a Camada A se mostrou hetereogênea com relação aos parâmetros de compressibilidade após 2,6m de profundidade. Observou-se o pré-adensamento dos solos moles e cv variando de 10-3 a 10-5 e ch de 10-2 a 10-3cm²/s. A maioria dos parâmetros geotécnicos obtidos se enquadram na tendência de comportamento dos demais solos brasileiros e catarinenses estudados. Os recalques monitorados alcançaram 78% dos calculados e os previstos através de métodos gráficos alcançaram de 90 a 133% dos recalques medidos. Dessa forma, verificou-se que existe a tendência de estabilização dos recalques no local de estudo.Abstract : In Brazil the deposits of soft soils are located along the coast, including the state of Santa Catarina, which is frequently observed in settlements due to the high compressibility of these soils. Currently with the advancement of technology through scientific research and the large urban settlements, areas of compressible soils, that first avoided the implementation of works, have been used as a viable alternative and are becoming increasingly common. Thus, this research aims to contribute to scientific advancement through studying the local soil in stratigraphic and geotechnical parameters and the density behavior of a soft soil, located in the city of Itajaí-SC. This study proposed to build a landfill in order to hedge against flooding of the River Itajaí-Acu reinforced with "geogrelhas" and "geodrenos" to accelerate settlements. Geotechnical parameters were obtained through field trials, with polls SPT, CPT, CPTu e DMT, laboratory characterization with Standard Incremental Consolidation (SIC) and Constant rate of Strain (CRS) , empirical correlations were also studied. Finally, the geotechnical parameters obtained were compared with other Brazilian studies. The densification behavior was studied by calculating settlements for thickening primary, monitoring of settlements through the geotechnical field instrumentation and also predictions of final settlements by application of graphical methods. The soil stratigraphy of the site consists of inserted layers of clay and sand, forming fluvial-marine and impenetrable soil after 30m deep. The first two layers of soft soil (Layer A and B) which the layer A has been shown with respect the heterogeneous compressibility parameters after 2.6 m in depth, were studied. Observed the pre-consolidation of soft soils and horsepower ranging from 10-3 to 10-5 and ch 10-2 of the 10-3cm²/s. Most geotechnical parameters obtained fall into the pattern of other Brazilian and Santa Catarina soils. Monitored repressions reached 78% of the calculated and the predicted graphical methods reached 90-133% of the measured settlements. Thus it was found that the tendency to stabilize at the study site repression
The 3-dimensional anatomy of the North-Western Marsupial Mole (Notoryctes caurinus Thomas 1920) using computed tomography, X-ray and magnetic resonance imaging
No full textThe 3-D skeletal images obtained from reconstruction of CT scans and X-rays, and soft-tissue images produced by MRI, provide invaluable information of the internal and gross anatomy of the north-western marsupial mole (Notoryetes caurinus).
The conical skull, which is quite thin-walled dorsally and anteriorly but strong in the basicranial region, has little evidence of the orbit or zygomatic arch, and the smoothly-curved posterior region has no sagittal or occipital crests. The vertebral column is remarkably strengthened, and in lateral view has an unusual flat-shape. The cervical vertebrae appear to be greatly compressed; 4 or 5 are completely fused (which is unique among marsupials). The thoracic vertebrae are fairly robust with large neural spines. The lumbar vertebrae are distinct, becoming large posteriorly towards the pelvis. The sacral vertebrae are greatly expanded in size and are fused with the pelvis. Particularly in the middle of the tail, the caudal vertebrae are greatly developed, with large transverse processes and chevron bones. The pectoral girdle is very anterior, with the shoulder articulation level with the anterior cervical vertebrae just behind the skull, and low on the side of the body. The humerus is robust, and the radius and ulna are very short. The bones of the pelvis are highly derived, and fused to sacral vertebrae. The epipubic bones are small and not ossified. An ossified patella is present and it has an unusual large triangular keel.
The most apparent soft-tissue structure by MRI is a large amount of subcutaneous fat, particularly around the ventral surface of the pelvis but also dorsal to the pelvis and anteriorly around the shoulders. The major muscle groups are visible, but distinction between individual muscles is not possible except for the very large muscles of the thigh, upper arm and base of the tail. The muscles of the tail are strongly developed, more so ventrally than dorsally
Ten reasons NOT to fix the numerical value of the Avogadro constant
No full textThis discussion paper, circulated in advance of the 17th meeting of the Consultative Committee for Amount of Substance, addresses the proposed redefinition of the mole in terms of a fixed numerical value for the Avogadro constant. It gives ten reasons why the Avogadro constant should not be given a fixed numerical value in the International System of Units, noting that there would be no metrological benefit from such a change, and that the proposed redefinition would be more conceptually complex that the current one and divorced from practical measurement and historical background. As the conditions for redefinition of the kilogram have not been met, and no mise en pratique has been produced for the proposed new definition, the paper concludes that the proposal should be rejected.

Phylogeny of African mole-rats.
No full text<p>(A) Phylogenetic relationships and approximate divergence times of African mole-rat species and one outgroup species (<i>Hystrix africaeaustralis</i>). Divergence times assume a molecular clock calibration of between 40 and 48 million years (myr) for the basal node within the family. The three species compared in the current study are members of the genera highlighted in blue. Adapted from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0007477#pone.0007477-Faulkes3" target="_blank">[29]</a>. (B–D) Photographs of a (B) Damaraland mole-rat (<i>Fukomys damarensis</i>), (C) silvery mole-rat (<i>Heliophobius argenteocinereus</i>), and (D) naked mole-rat (<i>Heterocephalus glaber</i>). Photograph credits: (B) and (C) by Sharry Goldman; (D) by Radim Šumbera.</p
External genitalia in three African mole-rat species.
No full text<p>Naked mole rat male (A) and female (B); Damaraland mole-rat male (C) and female (D); Silvery mole-rat male (E) female (F). Brackets indicate anogenital distance. Asterisk in B indicates site of the imperforate vagina. Abbreviations: A, anus; AM, anal mound; GM, genital mound; Ph, phallus. Scale bars: 3 mm for A–D; 2 mm for E and F.</p
Sexuality and nationality: homophobic discourse and the 'national threat' in contemporary Latvia
No full textThis paper considers why attitudes towards gays and lesbians in
Latvia appear to be more intolerant than in all other EU member states. The paper
argues that while the legacy of communist discourses on homosexuality and
the impact of post-communist transition have played a role in shaping attitudes
towards sexuality and sexual minorities in Central and Eastern Europe, these
factors cannot sufficiently explain the divergence among post-communist states
and, in particular, do not account for Latvia’s extreme position. While acknowledging
that intolerance towards non-heteronormative sexualities cannot be explained
by a single factor, the paper argues that homosexuality has become particularly
reviled in Latvia because it has been widely discursively constructed as
a threat to the continued existence of the nation
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
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