177,608 research outputs found
The Apostolis. A family of modern paremiologists in the XVIth century (part I: written evidences)
No full text
La porpora nel Sinassario di Costantinopoli. Imperatori ed imperatrici in odore di santità?
No full textA Genomic Approach to the Shade Avoidance Response in Arabidopsis
No full textEssendo organismi sessili, le piante hanno evoluto strategie molto sofisticate per la percezione dell’ambiente che le circonda nel loro habitat naturale, allo scopo di adattarvisi con il massimo profitto per la loro sopravvivenza e riproduzione. Le piante ottengono la loro energia dalla radiazione luminosa mediante il processo fotosintetico, e sono quindi particolarmente sensibili alla qualità e quantità della luce che le circonda, percependo in particolar modo la presenza della vegetazione circostante come un segnale di competizione per l’approvvigionamento luminoso. Infatti, crescendo in condizioni di ombreggiatura le piante percepiscono una luce filtrata nella sua componente più fotosinteticamente attiva, caratterizzata da una riduzione nel rapporto tra la radiazione nel rosso (R) e nel rosso lontano (FR) (basso R/FR), a cui reagiscono molto rapidamente aumentando la crescita in allungamento degli organi di sostegno della parte aerea (ipocotile, piccioli) a spese dello sviluppo di foglie e radici (risposta di “fuga dall’ombra”). Se la pianta ha successo nel suo tentativo di crescere al di sopra della vegetazione che la circonda, questa risposta va incontro ad una rapida reversione. D’altra parte, se il segnale persiste la pianta attenua la risposta attraverso l’azione del fattore di trascrizione bHLH HFR1/SICS1. In questo lavoro sono stati integrati studi globali di espressione genica mediante microarray ed analisi genetiche allo scopo di individuare molecole regolative implicate nel controllo della risposta di fuga dall’ombra. I nostri risultati hanno evidenziato che un numero significativo di regolatori trascrizionali sono rapidamente e transientemente indotti dalla luce con basso R/FR (fattori di trascrizione bHLH e HD-Zip). Le analisi condotte hanno anche messo in evidenza un nuovo meccanismo di controllo negativo della risposta di fuga dall’ombra che sembra agire attraverso il fattore di trascrizione bZip HY5. Analisi filogenetiche su alcuni dei regolatori trascrizionali della risposta di fuga dall’ombra (bHLH e HD-Zip II) ci hanno condotto alla loro classificazione in diverse sottofamiglie, caratterizzate da proteine con differenti capacità di legame al DNA e profili di espressione. I nostri risultati hanno identificato diversi cladi contenenti un piccolo numero di molecole molto simili tra loro regolate dalla qualità della luce ambientale. Ulteriori analisi saranno condotte per approfondire il ruolo di questi fattori e identificare i loro target molecolari durante la risposta di fuga dall’ombra
Magnetically Driven Baryon Winds from Binary Neutron Star Merger Remnants and the Blue Kilonova of 2017 August
No full textThe observation of a radioactively powered kilonova associated with the first binary neutron star (BNS) merger detected in gravitational waves proved that these events are ideal sites for the production of heavy r-process elements. However, the physical origin of the ejected material responsible for the early ("blue") and late ("red") components of this kilonova is still debated. Here, we investigate the possibility that the early/blue kilonova originated from the magnetically driven baryon wind launched after merger by the metastable neutron star remnant. Exploiting a magnetized BNS merger simulation with over 250 ms of post-merger evolution, we can follow for the first time the full mass-ejection process up to its final decline. We find that the baryon wind carries ≃0.010-0.028 M o ̇ of unbound material, proving that the high mass estimated for the blue kilonova can be achieved. We also find expansion velocities of up to ∼0.2c, consistent with the lower end of the observational estimates, and we discuss possible effects neglected here that could further increase the final ejecta velocity. Overall, our results show that the magnetically driven baryon wind represents a viable channel to explain the blue kilonova
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Sequence analysis of Isomin, a novel cytoplasmic intermediate filament protein from a basal arthropod species, the collembolan Isotomurus maculatus (Schaffer 1986)
No full textIsomin, An Arthropod Intermediate Filament Protein, is the main component of The Midgut Terminal Web and Interacts With apical Actin Cytoskeleton
No full text"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Short gamma-ray burst jet propagation in binary neutron star merger environments
No full textThe multimessenger event GW170817/GRB 170817A confirmed that binary neutron star (BNS) mergers can produce short gamma-ray burst (SGRB) jets. This evidence promoted new investigations on the mechanisms through which a BNS merger remnant can launch such a powerful relativistic outflow and on the propagation of the latter across the surrounding post-merger environment. In particular, great strides have been made in jet propagation models, establishing connections between the initial jet launching conditions, including the incipient jet launching time (with respect to merger) and the injection parameters, and the observable SGRB prompt and afterglow emission. However, present semi-analytical models and numerical simulations (with one notable exception) adopt simple handmade prescriptions to account for the post-merger environment, lacking a direct association with any specific merging BNS system. Here, we present the first three-dimensional relativistic hydrodynamics simulations of incipient SGRB jets propagating through a post-merger environment that is directly imported from the outcome of a previous general relativistic BNS merger simulation. Our results show that the evolution and final properties of the jet can be largely affected by the anisotropies and the deviations from axisymmetry and homologous expansion characterizing more realistic BNS merger environments. In addition, we find that the inclusion of the gravitational pull from the central compact object, often overlooked, can have a major impact. Finally, we consider different jet launching times referred to the same BNS merger model and discuss the consequences for the ultimate jet properties
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