276 research outputs found
ULTRASTRUCTURAL OBSERVATIONS ON SYMBIONT DEGENERATION IN THE MALE LINE OF PSEUDAULACASPIS PENTAGONA (TARGIONI TOZZETTI) (HEMIPTERA: COCCOIDEA: DIASPIDIDAE)
ULTRASTRUCTURAL OBSERVATIONS ON SYMBIONT DEGENERATION IN THE MALE LINE OF PSEUDAULACASPIS PENTAGONA (TARGIONI TOZZETTI) (HEMIPTERA: COCCOIDEA: DIASPIDIDAE).During the development of the immature stages of male scale insects, the mouthparts become lost at the prepupal stage and this is paralleled by the degeneration of the symbiont microorganisms inhabiting the mycetocytes. This degenerative process has been studied in the male line of the white peach scale, Pseudaulacaspis pentagona (Targioni Tozzetti). In the first two feeding instars, the mycetocytes appear as spherical cells, 30-40μm in diameter, filled with normal micro-organisms, round or oval in shape, 3-5μm long. In the prepupal and pupal stages, some symbionts undergo degeneration by a dissolution of the dense ribosomal granulations which characterize the microorganisms in the two feeding instars. In these symbionts, the fusing of the small vacuoles results in the appearance of larger, more centrally-placed, vacuoles. Other symbionts become loosely reticulated or, alternatively, condensed or contracted, to form regular or irregular bodies. The mycetocytes seem to undergo no reduction in size but their cytoplasm shows signs of dissolution as well. A great number of dense, crystalline-like granulations were found in their proximity. The nature and derivation of these granulations remains to be investigated.
The megalithic building of S.Erasmo di Cesi: architecture, astronomy, and landscape
Abstract. One of the most enigmatic megalithic buildings of Italy is the structure which lies on the S. Erasmo hill near Cesi, in Umbria, a huge complex encompassing an area of around 8000 square meters and enclosed by refined cyclopean walls. Although its date is uncertain, suggested dates comprise the Iron Age and archaic period, down to the third century B.C. The building’s function is also uncertain. Usually identified as a fortified structure, in fact there is a megalithic platform at the southern end of the enclosure which could have served as foundation of a temple or palace and, from the top of Monte Torre Maggiore, a complex of temples dating from the fourth century B.C. overlooks the hill. Similar combinations of megalithic buildings resting half-way to temples placed on high peaks are known to exist. In order to clarify the function of this structure and its position in relation to the surrounding landscape, with particular attention to its visibility and to the directions of visibility from the complex, as well as to the possible astronomical alignments, we present a multi-disciplinary approach to the study of the S. Erasmo complex, which includes the mapping of the sky at the various possible epochs of construction, the creation of a digital model of the landscape in forms of digital maps using Geographic Information System technologies, and a 3D model using various 3D software packages
Tick size and price diffusion
A tick size is the smallest increment of a security price. It is clear that
at the shortest time scale on which individual orders are placed the tick size
has a major role which affects where limit orders can be placed, the bid-ask
spread, etc. This is the realm of market microstructure and there is a vast
literature on the role of tick size on market microstructure. However, tick
size can also affect price properties at longer time scales, and relatively
less is known about the effect of tick size on the statistical properties of
prices. The present paper is divided in two parts. In the first we review the
effect of tick size change on the market microstructure and the diffusion
properties of prices. The second part presents original results obtained by
investigating the tick size changes occurring at the New York Stock Exchange
(NYSE). We show that tick size change has three effects on price diffusion.
First, as already shown in the literature, tick size affects price return
distribution at an aggregate time scale. Second, reducing the tick size
typically leads to an increase of volatility clustering. We give a possible
mechanistic explanation for this effect, but clearly more investigation is
needed to understand the origin of this relation. Third, we explicitly show
that the ability of the subordination hypothesis in explaining fat tails of
returns and volatility clustering is strongly dependent on tick size. While for
large tick sizes the subordination hypothesis has significant explanatory
power, for small tick sizes we show that subordination is not the main driver
of these two important stylized facts of financial market.Comment: To be published in the "Proceedings of Econophys-Kolkata V
International Workshop on "Econophysics of Order-driven Markets" March 9-13,
2010, The New Economic Windows series of Springer-Verlag Italia
Simultaneous Proton Transfer Reaction-Mass Spectrometry and electronic nose study of the volatile compounds released by Plasmodium falciparum infected red blood cells in vitro
The discovery that Volatile Organic Compounds (VOCs) can be biomarkers for several diseases has led to the conception of their possible application as diagnostic tools. In this study, we aimed at defining of diagnostic signatures for the presence of malaria transmissible stages in infected individuals. To do this, we compared VOCs released by asexual and sexual stage cultures of Plasmodium falciparum, the deadliest species of malaria, with those emitted by uninfected red blood cells (RBCs). VOC analysis was carried out with an innovative set-up, where each sample was simultaneously analysed by proton transfer reaction time of flight mass spectrometry (PTR-ToF-MS) and an electronic nose. PTR-Tof-MS results show that sexual stages are characterized by a larger emission of hexanal, compared with uninfected or asexual stage-infected RBCs, which makes them clearly identifiable. PTR-Tof-MS analysis also detected differences in VOC composition between asexual stages and uninfected RBCs. These results have been substantially replicated by the electronic nose analysis and may open the possibility to develop sensitive and easy-to-use devices able to detect sexual parasite stages in infected individuals. This study also demonstrates that the combination of mass spectrometry with electronic noses is a useful tool to identify markers of diseases and to support the development of optimized sensors
14q12q13.2 microdeletion syndrome: Clinical characterization of a new patient, review of the literature, and further evidence of a candidate region for CNS anomalies
Background: Chromosome 14q11-q22 deletion syndrome (OMIM 613457) is a rare contiguous gene syndrome. Two regions of overlap (RO) of the 14q12q21.1 deletion have been identified: a proximal region (RO1), including FOXG1(*164874), NKX2-1(*600635), and PAX9(*167416) and a distal region (RO2), including NKX2-1 and PAX9. We report a 6-year-old boy with mild dysmorphic facial features, global developmental delay, and hypoplasia of the corpus callosum. Methods and Results: Array-CGH analysis revealed a 14q12q13.2 microdeletion. We compared the phenotype of our patient with previously published cases in order to establish a genotype–phenotype correlation. Conclusion: The study hypothesizes the presence of a new RO, not including the previously reported candidate genes, and attempt to define the associated molecular and psychomotor/neurobehavioral phenotype. This region encompasses the distal breakpoint of RO1 and the proximal breakpoint of RO2, and seems to be associated with intellectual disability (ID), hypotonia, epilepsy, and corpus callosum abnormalities. Although more cases are needed, we speculated on SNX6(*606098) and BAZ1A(*605680) as potential candidate genes associated with the corpus callosum abnormalities
Malaria transmission through the mosquito requires the function of the OMD protein
Ookinetes, one of the motile and invasive forms of the malaria parasite, rely on gliding motility in order to establish an infection in the mosquito host. Here we characterize the protein PBANKA_0407300 which is conserved in the Plasmodium genus but lacks significant similarity to proteins of other eukaryotes. It is expressed in gametocytes and throughout the invasive mosquito stages of P. berghei, but is absent from asexual blood stages. Mutants lacking the protein developed morphologically normal ookinetes that were devoid of productive motility although some stretching movement could be detected. We therefore named the protein Ookinete Motility Deficient (OMD). Several key factors known to be involved in motility however were normally expressed and localized in the mutant. Importantly, the mutant failed to establish an infection in the mosquito which resulted in a total malaria transmission blockade
Combinatorial effects on gene expression at the Lbx1/Fgf8 locus resolve Split-Hand/Foot Malformation type 3
Split-Hand/Foot Malformation type 3 (SHFM3) is a congenital limb malformation associated with tandem duplications at the LBX1/FGF8 locus. Yet, the disease patho-mechanism remains unsolved. Here we investigated the functional consequences of SHFM3-associated rearrangements on chromatin conformation and gene expression in vivo in transgenic mice. We show that the Lbx1/Fgf8 locus consists of two separate, but interacting, regulatory domains. Re-engineering of a SHFM3-associated duplication and a newly reported inversion in mice resulted in restructuring of the chromatin architecture. This led to an ectopic activation of the Lbx1 and Btrc genes in the apical ectodermal ridge (AER) in an Fgf8-like pattern. Artificial repositioning of the AER-specific enhancers of Fgf8 was sufficient to induce misexpression of Lbx1 and Btrc. We provide evidence that the SHFM3 phenotype is the result of a combinatorial effect on gene misexpression and dosage in the developing limb. Our results reveal new insights into the molecular mechanism underlying SHFM3 and provide novel conceptual framework for how genomic rearrangements can cause gene misexpression and disease
syk inhibitors interfere with erythrocyte membrane modification during p falciparum growth and suppress parasite egress
Key Points
Inhibitors of human Syk kinase suppress parasite egress. Syk inhibitors prevent the tyrosine phosphorylation of band 3 in P falciparum parasitized red blood cells, reducing the release of microparticles
Klassische Moderne. Un paradigma del Novecento
Il libro, che pubblica gli atti del convegno internazionale, svoltosi a Roma nel maggio del 2007 nell’ambito della ricerca PRIN-2005 (Università di Roma La Sapienza, Trento, Bari e Urbino), analizza il periodo della cultura tedesca della fine-secolo con particolare attenzione ai personaggi e ai movimenti che si sono collocati negli “spazi intermedi”, intesi non solo e non tanto come zone di confine in senso territoriale, quanto piuttosto come zone di interscambio culturale e disciplinare, come tentativi di “superamento” degli ordini mentali e culturali costituiti. L’ambito cronologico che il gruppo di ricerca prende in esame va da 1888 al 1933. La periodizzazione proposta vuole rinviare a quella serie di movimenti e di pensatori che hanno dato il via alla messa in discussione di quei valori costituiti, dalla cui frammentazione è nata la cultura del “secolo breve”.
In questo periodo, a partire dalla Jahrhundertwende, sono state elaborate e sperimentate nella prassi letteraria e artistica, una serie di teorie, una serie di “visioni del mondo” che implicavano tanto una pratica produttiva quanto un ruolo dell’artista e dell’arte quanto una visione più generale dei cambiamenti epocali e dell’epoca moderna. Tali teorie e pratiche artistiche, di vario genere e di vario livello, costituiscono un patrimonio concettuale perché in esse si trovano sperimentate e a volte anticipate molte questioni che oggi sono di estrema attualità: dal rapporto uomo-macchina al rapporto parola-immagine, dalla definizione degli spazi urbani alla questione della guerra, dalla ricerca della identità monoculturale alla presa d’atto dell’esistenza dell’estraneo. Queste varie problematiche sono state espresse in termini linguistici nuovi giacché gli autori si sono posti – teoricamente e praticamente – il problema del linguaggio artistico e ne hanno modificato (a volte radicalmente) i codici espressivi.
Il libro di divide in tre parti: I: Per una definizione della Klassische Moderne che presenta l’ampia e animata discussione sulla stessa definizione teorica del movimento artistico-culturale, sia sui termini cronologici di questa nuova periodizzazione. Questa parte raccoglie i contributi di Aldo Venturelli, Helmut Kiesel e Fabrizio Cambi. II: La rivoluzione delle forme, che analizza la produzione delle avanguardie (sia pure definite “marginali” ) e prende in considerazione anche aspetti della produzione musicale, nonché forme di narratologia e nuove forme di scrittura. Questa seconda parte pubblica i saggi di Mauro Ponzi, Rosmarie Keller, Silvio Vietta, Hans Dieter Zimmermann, Elio Matassi e Sabine Meine. III: La fucina dei nuovi linguaggi che analizza l’innovazione dei linguaggi artistici sull’esempio di autori meno radicali che quelli delle avanguardie storiche. Questi autori, tipici esponenti della Klassische Moderne, hanno cercato di coniugare l’innovazione dei linguaggi con il recupero di alcuni aspetti della tradizione. Nella terza parte del volume vengono pubblicati i saggi di Alain Montandon, Giovanni Tateo, Gouseppe Farese, Gabriella Rovagnati, Sabine Schneider e Alessandro Fambrini
Acetylacetone photodynamics at a seeded freeelectron laser
The first steps in photochemical processes, such as photosynthesis or animal vision, involve changes in electronic and geometric structure on extremely short time scales. Time-resolved photoelectron spectroscopy is a natural way to measure such changes, but has been hindered hitherto by limitations of available pulsed light sources in the vacuum-ultraviolet and soft Xray spectral region, which have insufficient resolution in time and energy simultaneously. The unique combination of intensity, energy resolution, and femtosecond pulse duration of the FERMI-seeded free-electron laser can now provide exceptionally detailed information on photoexcitation–deexcitation and fragmentation in pump-probe experiments on the 50- femtosecond time scale. For the prototypical system acetylacetone we report here electron spectra measured as a function of time delay with enough spectral and time resolution to follow several photoexcited species through well-characterized individual steps, interpreted using state-of-the-art static and dynamics calculations. These results open the way for investigations of photochemical processes in unprecedented detail
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