10,433 research outputs found
Discovery of VHE and HE emission from the blazar 1ES 0414+009 with H.E.S.S and Fermi-LAT
The high energy peaked BL Lac (HBL) object 1ES 0414+009 (z=0.287) is a
distant very high-energy (VHE, E > 100 GeV) blazars with well-determined
redshift. This source was detected with the High Energy Stereoscopic System
(H.E.S.S.) between October 2005 and September 2009. It was also detected with
the Fermi Large Area Telescope (LAT) in 21 months of data. The combined high
energy (HE) and VHE spectra, once corrected for gamma-gamma absorption on the
extragalactic background light (EBL), indicate a Compton peak located above few
TeV, among the highest in the BL Lac class.Comment: proceeding from the 25th Texas Symposium on Relativistic Astrophysics
(Heidelberg, Germany, 2010
Paint Relics on Middle Age Building Stones as Proxies of Commercial Routes and Artistic Exchanges: A Multi-Analytical Investigation
Fifty-four pieces out of 356 marble pieces deriving from the decorative and architectonic apparatus of the medieval monastic complex of S. Francesco of Castelletto (Genoa, Italy) preserve traces of varicolored paint layers. Microscopic samples of green, blue, red, pink, white, and yellow paint relics were collected by scalpel and analyzed by means of Scanning Electron Microscope coupled with Energy Dispersive Spectroscopy (SEM-EDS), \u3bc-Raman, and Fourier Transform Infra- Red Spectroscopy with Attenuated Total Reflection (FTIR-ATR), to characterize pigments and binders. The combined results from the different techniques allowed verification that stone decoration in Genoa during the Middle Ages encompassed a calcite groundwork and the use of a mixture of oils and proteins (probably egg) to apply pigments. The assemblage of impurities within the pigment has been correlated with the provenance sites along the commercial continental (Hungary and France) and maritime (Sardinia, Cyprus, or Veneto) routes between the 13th and 15th centuries. Moreover, the investigation of the painted layer improved the characterization of the decorative techniques in use in Genoa during the Middle Ages
Autotrophic and Heterotrophic Growth Conditions Modify Biomolecole Production in the Microalga Galdieria sulphuraria (Cyanidiophyceae, Rhodophyta)
Algae have multiple similarities with fungi, with both belonging to the Thallophyte, a polyphyletic group of non-mobile organisms grouped together on the basis of similar characteristics, but not sharing a common ancestor. The main difference between algae and fungi is noted in their metabolism. In fact, although algae have chlorophyll-bearing thalloids and are autotrophic organisms, fungi lack chlorophyll and are heterotrophic, not able to synthesize their own nutrients. However, our studies have shown that the extremophilic microalga Galderia sulphuraria (GS) can also grow very well in heterotrophic conditions like fungi. This study was carried out using several approaches such as scanning electron microscope (SEM), gas chromatography/mass spectrometry (GC/MS), and infrared spectrophotometry (ATR-FTIR). Results showed that the GS, strain ACUF 064, cultured in autotrophic (AGS) and heterotrophic (HGS) conditions, produced different biomolecules. In particular, when grown in HGS, the algae (i) was 30% larger, with an increase in carbon mass that was 20% greater than AGS; (ii) produced higher quantities of stearic acid, oleic acid, monounsaturated fatty acids (MUFAs), and ergosterol; (iii) produced lower quantities of fatty acid methyl esters (FAMEs) such as methyl palmytate, and methyl linoleate, saturated fatty acids (SFAs), and poyliunsaturated fatty acids (PUFAs). ATR-FTIR and principal component analysis (PCA) statistical analysis confirmed that the macromolecular content of HGS was significantly different from AGS. The ability to produce different macromolecules by changing the trophic conditions may represent an interesting strategy to induce microalgae to produce different biomolecules that can find applications in several fields such as food, feed, nutraceutical, or energy production
Enhanced propagation of motile bacteria on surfaces due to forward scattering
How motile bacteria move near a surface is a problem of fundamental biophysical interest and is key to the emergence of several phenomena of biological, ecological and medical relevance, including biofilm formation. Solid boundaries can strongly influence a cell's propulsion mechanism, thus leading many flagellated bacteria to describe long circular trajectories stably entrapped by the surface. Experimental studies on near-surface bacterial motility have, however, neglected the fact that real environments have typical microstructures varying on the scale of the cells' motion. Here, we show that micro-obstacles influence the propagation of peritrichously flagellated bacteria on a flat surface in a non-monotonic way. Instead of hindering it, an optimal, relatively low obstacle density can significantly enhance cells' propagation on surfaces due to individual forward-scattering events. This finding provides insight on the emerging dynamics of chiral active matter in complex environments and inspires possible routes to control microbial ecology in natural habitats
Enhanced relativistic-electron beam collimation using two consecutive laser pulses
The double laser pulse approach to relativistic electron beam (REB)
collimation has been investigated at the LULI-ELFIE facility. In this scheme,
the magnetic field generated by the first laser-driven REB is used to guide a
second delayed REB. We show how electron beam collimation can be controlled by
properly adjusting laser parameters. By changing the ratio of focus size and
the delay time between the two pulses we found a maximum of electron beam
collimation clearly dependent on the focal spot size ratio of the two laser
pulses and related to the magnetic field dynamics. Cu-K alpha and CTR imaging
diagnostics were implemented to evaluate the collimation effects on the
respectively low energy ( MeV) components of the
REB
Crack path and damage in a CuZnAl SMA
Abstract: Pseudo-elastic (PE) materials are an important class of metallic alloy which exhibit unique features with respect to common engineering metals. In particular, due to these properties PEs are able to recover their original shape after high values of mechanical deformations, by removing the mechanical load (PE). From the microstructural point of view shape memory and pseudo-elastic effects are due to a reversible solid state microstructural diffusionless transitions from austenite to martensite, which can be activated by mechanical and/or thermal loads. Copper-based shape memory alloys are preferred for their good memory properties and low cost of production. In this work the main crack initiation and its propagation in a tensile test is analyzed in order to evaluate crack path and its behavior at low and at high values of deformation. Results are also associated both to grains boundary chemical properties and to X-ray diffraction, in order to correlate structural transition involved in an Cu-Zn-Al alloy characterized by a PE behavior
Time evolution of stimulated Raman scattering and two-plasmon decay at laser intensities relevant for shock ignition in a hot plasma
Laser–plasma interaction (LPI) at intensities 1015–1016 W cm2 is dominated by parametric instabilities which can be
responsible for a significant amount of non-collisional absorption and generate large fluxes of high-energy nonthermal
electrons. Such a regime is of paramount importance for inertial confinement fusion (ICF) and in particular for the
shock ignition scheme. In this paper we report on an experiment carried out at the Prague Asterix Laser System (PALS)
facility to investigate the extent and time history of stimulated Raman scattering (SRS) and two-plasmon decay (TPD)
instabilities, driven by the interaction of an infrared laser pulse at an intensity 1:2 1016 W cm2 with a 100 mm
scalelength plasma produced from irradiation of a flat plastic target. The laser pulse duration (300 ps) and the high
value of plasma temperature (4 keV) expected from hydrodynamic simulations make these results interesting for a
deeper understanding of LPI in shock ignition conditions. Experimental results show that absolute TPD/SRS, driven at
a quarter of the critical density, and convective SRS, driven at lower plasma densities, are well separated in time, with
absolute instabilities driven at early times of interaction and convective backward SRS emerging at the laser peak and
persisting all over the tail of the pulse. Side-scattering SRS, driven at low plasma densities, is also clearly observed.
Experimental results are compared to fully kinetic large-scale, two-dimensional simulations. Particle-in-cell results,
beyond reproducing the framework delineated by the experimental measurements, reveal the importance of filamentation
instability in ruling the onset of SRS and stimulated Brillouin scattering instabilities and confirm the crucial role of
collisionless absorption in the LPI energy balance
Nuove applicazioni per le unitĂ abitative in emergenza: tecnologie e tecniche della tradizione costruttiva andina amazonica
This work reports the result of a research activity conducted in Bolivia in the year
2020, in synergy between Bolivian Polytechnic University School "Josè Maria Nunez
del Prado", University of Naples Federico II and Pegaso Telematic University. In
particular, the research had as its object the study of a housing unit suitable for
coping with the floods that frequently afflict some Bolivian peasant populations.
During the research, much attention was initially paid to the historical, political,
socio-economic aspects and to the cultural and traditional characteristics of the
ethnic groups that make up the population of Bolivia; subsequently, the
morphology and hydrography of the Bolivian territory were examined, as well as
the climate, the trend of rainfall and the El Niño and La Niña phenomena that often
cause floods with serious risks for the populations, especially rural ones.
Having completed these first two phases of the research, the authors moved on to
the study of the traditional construction characteristics of rural architecture, paying
particular attention to the basic construction materials used in the peasant areas
of Bolivia, in particular to raw earth and bamboo, as well as the principles and
rules that regulate the construction of rural housing in Bolivia.
For rural architecture, the traditional Pawichi house and the traditional dwellings
of the indigenous Chiquitana population were examined in detail.
Only after having acquired all these important aspects, the research became
interested in the design of a new rural house which, respecting Bolivian cultural
traditions, would be able to cope with floods and reduce the risks associated with
them.
In the design of this new emergency housing unit, the authors focused their
attention not only on the compositional and functional aspects of the housing unit,
but also on the constructive aspects by designing new structural elements such as
the pillars made with five bamboo canes suitably linked together. with knots of the
Andean construction tradition.
The composition of the housing unit proposed by the authors is governed by a
basic 4x4 module that can be full, or delimited by infill and window frames, or
empty, or without surrounding infill elements to allow the creation of the traditional
place for socialization, the Punilla.
Never as in this case have, I been particularly happy with the invitation formulated
by the authors, and in particular by the young researchers, Francesca Volpe and
Emanuele La Mantia, to present their work.
In fact, I was able to see the procedural quality of the research and the intelligent
design procedure that led to the definition of a housing prototype of great interest
for the Andean populations
Electrochemical biosensors based on nanomodified screen-printed electrodes: Recent applications in clinical analysis
This review addresses recent advances in the development of screen-printed electrode based biosensors modified with different nanomaterials such as carbon nanotubes, graphene, metallic nanoparticles as gold, silver and magnetic nanoparticles, and mediator nanoparticles (Prussian Blue, Cobalt Phthalocyanine, etc.), coupled with biological recognition elements such as enzymes, antibodies, DNA and aptamers to obtain probes with improved analytical features. Examples of clinical applications are illustrated, together with examples of paper-based electrochemical devices, of multiple detections using arrays of screen printed electrodes, and of the most recent developments in the field of wearable biosensors. Also the use of smartphones as final detectors is briefly depicted. © 2016 Elsevier B.V
- …