891 research outputs found
Application of novel techniques for interferogram analysis to laser-plasma femtosecond probing
Recently, two novel techniques for the extraction of the phase-shift map
(Tomassini {\it et.~al.}, Applied Optics {\bf 40} 35 (2001)) and the electronic
density map estimation (Tomassini P. and Giulietti A., Optics Communication
{\bf 199}, pp 143-148 (2001)) have been proposed. In this paper we apply both
methods to a sample laser-plasma interferogram obtained with femtoseconds probe
pulse, in an experimental setup devoted to laser particle acceleration studies.Comment: Submitted to Laser and Particle Beam
Analysis of space-resolved X-ray spectra from laser plasmas
High dynamic range, space-resolved X-ray spectra, obtained
using a TlAP crystal and a cooled CCD camera as a detector,
were used to investigate the electron density and temperature
profiles of an aluminum laser plasma with micrometer resolution.
The electron density profile retrieved from the measurements
is compared with numerical predictions from the two hydrodynamics
codes MEDUSA (1D) and POLLUX (2D). It is shown that 2D density
profiles can be successfully reproduced by 1D simulations using
a spherical geometry with an ad hoc initial radius, leading
to similar electron temperature profiles
Quantitative global-local mixing for accessible skew products
We study global-local mixing for accessible skew products with a mixing base.
For a dense set of almost periodic global observables, we prove rapid mixing;
and for a dense set of global observables vanishing at infinity, we prove
polynomial mixing. More generally, we relate the speed of mixing to the "low
frequency behaviour" of the spectral measure associated to our global
observables. Our strategy relies on a careful choice of the spaces of
observables and on the study of a family of twisted transfer operators
Complete (k,3)-arcs from quartic curves
Complete (Formula presented.) -arcs in projective planes over finite fields are the geometric counterpart of linear non-extendible Near MDS codes of length (Formula presented.) and dimension (Formula presented.). A class of infinite families of complete (Formula presented.) -arcs in (Formula presented.) is constructed, for (Formula presented.) a power of an odd prime (Formula presented.). The order of magnitude of (Formula presented.) is smaller than (Formula presented.). This property significantly distinguishes the complete (Formula presented.) -arcs of this paper from the previously known infinite families, whose size differs from (Formula presented.) by at most (Formula presented.)
A study of laser plasmas as X-ray sources in the 1-10 keV spectral region
An experimental investigation on X-ray emission from laser-produced plasmas is presented and the properties of such an emission of interest for application purposes are examined. Plasmas were generated by focusing 1 ÎŒm, 3 ns Nd laser pulses onto Al and Cu targets at an intensity of 1013 W/cm2. The temporal evolution of the emission and its spectral features were investigated by using an X-ray streak-camera and an X-ray photodiode. In the case of Cu targets, the analysis of the emission showed two spectral components. The main component was centered at â 1.2 keV and a minor component, whose intensity was measured to be 10-3 of the previous component, was observed at â7 keV. The X-ray conversion efficiency, in the investigated spectral region, was measured to be 1% for Cu targets and 0.3% for Al targets
Gorceixia decurrens (Compositae: Vernonieae): nova espécie para o estado da Bahia, Brasil
Recent fieldwork and collections have added a new genus to the Compositae flora of Bahia State, Brazil. Gorceixia decurrens is newly recorded for the State from Caatinga woodland along the lower part of the Estrada Real, in the municipality of Rio de Contas. A full description is provided, its distribution and conservation status discussed; likely affinities in the Vernonieae are discussed with the conclusion that it belongs to the subtribe Piptocarphinae.Trabalhos de campo e coletas recentes na Bahia, Brasil, permitiram adicionar mais um gĂȘnero para a flora do Estado. Gorceixia decurrens foi coletada em 2001, em ĂĄrea de Caatinga ArbĂłrea, na base da Estrada Real no municĂpio a Rio de Contas. Ă fornecida uma completa descrição da espĂ©cie e discussĂŁo sobre sua distribuição e estado de conservação. TambĂ©m, Ă© apresentada discussĂŁo do posicionamento do gĂȘnero monotĂpico nas Vernonieae concluindo-se que o mesmo pertence Ă subtribo Piptocarphinae
Acceleration with Self-Injection for an All-Optical Radiation Source at LNF
We discuss a new compact gamma-ray source aiming at high spectral density, up
to two orders of magnitude higher than currently available bremsstrahlung
sources, and conceptually similar to Compton Sources based on conventional
linear accelerators. This new source exploits electron bunches from
laser-driven electron acceleration in the so-called self-injection scheme and
uses a counter-propagating laser pulse to obtain X and gamma-ray emission via
Thomson/Compton scattering. The proposed experimental configuration inherently
provides a unique test-bed for studies of fundamental open issues of
electrodynamics. In view of this, a preliminary discussion of recent results on
self-injection with the FLAME laser is also given.Comment: 8 pages, 10 figures, 44 references - Channeling 2012 conferenc
A novel PIEZO1 mutation in a patient with dehydrated hereditary stomatocytosis: A case report and a brief review of literature
open7noThis work was supported by EHA Junior Research Grant to Immacolata Andolfo (3978026), and by Bando Star Linea 1 - JUNIOR PRINCIPAL INVESTIGATOR GRANTS - COINOR, UniversitĂ degli Studi di Napoli Federico II to Roberta Russo.Background: Dehydrated hereditary stomatocytosis (DHS) or hereditary xerocytosis is a rare, autosomal dominant hemolytic anemia characterized by macrocytosis, presence of stomatocytes and dehydration of red blood cells (RBCs). The dehydration is caused by a defect in cellular cation content. The most frequent expression of the pathology is hemolytic well-compensated anemia with high reticulocyte count, a tendency to macrocytosis, increased mean corpuscular hemoglobin concentration (MCHC) and mild jaundice. We here describe a new mutation of PIEZO1 gene, the most frequent mutated gene in DHS, in a family affected by hereditary hemolytic anemia. Case presentation: We describe the case of a 12-years-old girl with well-compensated chronic hemolysis, increased MCHC and a father who had the same hematological characteristics. After excluding secondary causes of chronic hemolysis and enzymatic defects of the RBCs, microscopic observation of the peripheral blood smear, tests of RBC lysis, ektacytometry, SDS-PAGE and in last instance genetic analysis has been performed. This complex diagnostic workup identified a new variant in the PIEZO1 gene, never described in literature, causative of DHS. This pathogenetic variant was also detected in the father. Conclusions: This case report highlights the importance of a correct and exhaustive diagnostic-workup in patients with clinical suspicious for hemolytic anemia in order to make a differential diagnosis. This is relevant for the management of these patients because splenectomy is contraindicated in DHS due to high thrombotic risk.openZama D.; Giulietti G.; Muratore E.; Andolfo I.; Russo R.; Iolascon A.; Pession A.Zama D.; Giulietti G.; Muratore E.; Andolfo I.; Russo R.; Iolascon A.; Pession A
Real-time optical manipulation of cardiac conduction in intact hearts
Optogenetics has provided new insights in cardiovascular research, leading to new methods for cardiac pacing, resynchronization therapy and cardioversion. Although these interventions have clearly demonstrated the feasibility of cardiac manipulation, current optical stimulation strategies do not take into account cardiac wave dynamics in real time. Here, we developed an allâoptical platform complemented by integrated, newly developed software to monitor and control electrical activity in intact mouse hearts. The system combined a wideâfield mesoscope with a digital projector for optogenetic activation. Cardiac functionality could be manipulated either in freeârun mode with submillisecond temporal resolution or in a closedâloop fashion: a tailored hardware and software platform allowed realâtime intervention capable of reacting within 2 ms. The methodology was applied to restore normal electrical activity after atrioventricular block, by triggering the ventricle in response to optically mapped atrial activity with appropriate timing. Realâtime intraventricular manipulation of the propagating electrical wavefront was also demonstrated, opening the prospect for realâtime resynchronization therapy and cardiac defibrillation. Furthermore, the closedâloop approach was applied to simulate a reâentrant circuit across the ventricle demonstrating the capability of our system to manipulate heart conduction with high versatility even in arrhythmogenic conditions. The development of this innovative optical methodology provides the first proofâofâconcept that a realâtime optically based stimulation can control cardiac rhythm in normal and abnormal conditions, promising a new approach for the investigation of the (patho)physiology of the heart
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