2,088 research outputs found
Giant and time-dependent magnetocaloric effect in high-spin molecular magnets
We have measured and calculated the magnetocaloric effect in macroscopic
samples of oriented high-spin molecular clusters like Mn12 and Fe8 as a
function of the temperature and both the intensity and the sweeping rate of the
applied magnetic field. We have observed a high magnetic entropy variation
around the blocking temperature of the magnetic moment of molecules and
calculated the shift of the entropy variation and cooling temperature, with the
sweeping rate of the magnetic field.Comment: 10 pages, 3 figure
Interplay between long non-coding RNAs and epigenetic machinery: emerging targets in cancer?
Of the diverse array of putative molecular and biological functions assigned to long non-coding RNAs (lncRNAs), one attractive perspective in epigenetic research has been the hypothesis that lncRNAs directly interact with the proteins involved in the modulation of chromatin conformation. Indeed, epigenetic modifiers are among the most frequent protein partners of lncRNAs that have been identified to date, of which histone methyltransferases and protein members of the Polycomb Repressive Complex PRC2 have received considerable attention. This review is focused on how lncRNAs interface with epigenetic factors to shape the outcomes of crucial biological processes such as regulation of gene transcription, modulation of nuclear architecture, X inactivation in females and pre-mRNA splicing. Because of our increasing knowledge of their role in development and cellular differentiation, more research is beginning to be done into the deregulation of lncRNAs in human disorders. Focusing on cancer, we describe some key examples of disease-focused lncRNA studies. This knowledge has significantly contributed to our ever-improving understanding of how lncRNAs interact with epigenetic factors of human disease, and has also provided a plethora of much-needed novel prognostic biomarker candidates or potential therapeutic targets. Finally, current limitations and perspectives on lncRNA research are discussed here. This article is part of a discussion meeting issue 'Frontiers in epigenetic chemical biology'
Nueva técnica de pegado con resina acrílica para preparar láminas delgadas para microscopía óptica
[ES] Tras un breve análisis de 10s pegamentos mis utilizados en la
preparación de Iáminas delgadas de materiales geológicos con sus
ventajas e inconvenientes, se describe un método de encolado
rápido y fiable con resina acrilica. Se presenta además un diseño
sencillo de una prensa con base de vidrio que permite el paso de la
luz ultravioleta indispensable para el endurecimiento de la resina.
La preparaciói? de láminas delgadas con diferentes tipos de rocas
coherentes y sedimentos y suelos impregnados, asi como las pruebas
sobre la calidad de las uniones, su resistencia al mecanizado, el
indice de refracción de la resina y el envejecimiento, han dado
resultados altamente satisfactorios.[EN] After a short comparative analysis of the most usual bonding
techniques for rock thin section preparation, a new fast and reliable
bonding technique with acrylic resin is described.
A new design for a U.V. translucent press necessary for both a
minimun glue thickness and as a requirement for the acrylic bonding
to be completed, is also presented. Tests about thin section quality, mechanical resistance of the bond, refractive index and ageing
performed on different hard rocks and impregnated sediments and
soils, have given excellent results.Peer reviewe
Psychological Pathways to Paranoia and Psychotic-Like Experiences in Daily-Life : The Mediating Role of Distinct Affective Disturbances
Influential models of psychosis indicate that the impact of putative causal factors on positive symptoms might be explained partly through affective disturbances. We aimed to investigate whether pathways from stress and self-esteem to positive symptoms, as well as reversal pathways from symptoms to stress and self-esteem, were mediated through specific affective disturbances across the extended psychosis phenotype. Using experience sampling methodology, 178 participants (65 high-schizotypy, 74 at-risk mental state, and 39 first-episode psychosis) were assessed on levels of momentary stress, self-esteem, anxiety, sadness, psychotic-like experiences (PLE), and paranoia. Multilevel mediation models were fit to examine indirect effects of each of these pathways. Considering evidence of mediation, each indirect pathway will be combined in a single model to explore their relative contributions. Anxiety, sadness, and self-esteem mediated the pathways from stress to PLE and paranoia in daily-life. In the pathway to paranoia, sadness, and self-esteem showed larger contributions than anxiety. Pathways from self-esteem to PLE and paranoia were mediated by anxiety and sadness, the later showing a larger contribution. Pathways from symptoms to stress, but not from symptoms to self-esteem, were differently explained by emotional states; sadness lost its mediating effect and anxiety was the most important mediator. Few differences across groups were found. This study lends support to psychological models of psychosis that highlight the relevance of affective disturbances in the risk and expression of psychosis. Furthermore, specific influences of different negative emotional states were identified, which could enhance psychological treatments
Cutaneous Leishmaniasis, Sri Lanka
Cutaneous leishmaniasis (CL) is an emerging disease in Sri Lanka. Of 116 patients with clinical symptoms suggestive of CL, 86 were confirmed positive for Leishmania donovani. Most patients had single dry lesions, usually on the face. Patients were from 5 of the 7 agroclimatic zones in Sri Lanka
The role of temperature in the magnetic irreversibility of type-I Pb superconductors
Evidence of how temperature takes part in the magnetic irreversibility in the
intermediate state of a cylinder and various disks of pure type-I
superconducting lead is presented. Isothermal measurements of first
magnetization curves and magnetic hysteresis cycles are analyzed in a reduced
representation that defines an equilibrium state for flux penetration in all
the samples and reveals that flux expulsion depends on temperature in the disks
but not in the cylinder. The magnetic field at which irreversibility sets in
along the descending branch of the hysteresis cycle and the remnant
magnetization at zero field are found to decrease with temperature in the
disks. The contributions to irreversibility of the geometrical barrier and the
energy minima associated to stress defects that act as pinning centers on
normal-superconductor interfaces are discussed. The differences observed among
the disks are ascribed to the diverse nature of the stress defects in each
sample. The pinning barriers are suggested to decrease with the magnetic field
to account for these results
3D RMHD simulations of jet-wind interactions in high-mass X-ray binaries
Context. Relativistic jets are ubiquitous in the Universe. In microquasars, especially in high-mass X-ray binaries, the interaction of jets with the strong winds driven by the massive and hot companion star in the vicinity of the compact object is fundamental for understanding the jet dynamics, nonthermal emission, and long-term stability. However, the role of the jet magnetic field in this process is unclear. In particular, it is still debated whether the magnetic field favors jet collimation or triggers more instabilities that can jeopardize the jet evolution outside the binary. Aims. We study the dynamical role of weak and moderate to strong toroidal magnetic fields during the first several hundred seconds of jet propagation through the stellar wind, focusing on the magnetized flow dynamics and the mechanisms of energy conversion. Methods. We developed the code Lóstrego v1.0, a new 3D relativistic magnetohydrodynamics code to simulate astrophysical plasmas in Cartesian coordinates. Using this tool, we performed the first 3D relativistic magnetohydrodynamics numerical simulations of relativistic magnetized jets propagating through the clumpy stellar wind in a high-mass X-ray binary. To highlight the effect of the magnetic field in the jet dynamics, we compared the results of our analysis with those of previous hydrodynamical simulations. Results. The overall morphology and dynamics of weakly magnetized jet models is similar to previous hydrodynamical simulations, where the jet head generates a strong shock in the ambient medium and the initial overpressure with respect to the stellar wind drives one or more recollimation shocks. On the timescales of our simulations (i.e., t < 200 s), these jets are ballistic and seem to be more stable against internal instabilities than jets with the same power in the absence of fields. However, moderate to strong toroidal magnetic fields favor the development of current-driven instabilities and the disruption of the jet within the binary. A detailed analysis of the energy distribution in the relativistic outflow and the ambient medium reveals that magnetic and internal energies can both contribute to the effective acceleration of the jet. Moreover, we verified that the jet feedback into the ambient medium is highly dependent on the jet energy distribution at injection, where hotter, more diluted and/or more magnetized jets are more efficient. This was anticipated by feedback studies in the case of jets in active galaxies
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