171,291 research outputs found
MUTATIONS IN THE VP1 CODING REGION OF POLYOMAVIRUS DETERMINE DIFFERENTIATING STAGE SPECIFICITY
No full textPolyomavirus mutants capable of replicating in undifferentiated murine C2 myoblasts were selected and characterized. These mutants grow normally in 3T6 mouse fibroblast cells, and they do not complement the wild-type virus in coinfection experiments of C2 myoblasts. Of 12 isolates, 10 possess duplications of the regulatory region including the enhancer A domain. On the bases of the regulatory region structure and the presence and length of the enhancer duplication, the mutant viruses could be grouped into three classes. One mutant class (e.g., PyMB3) possesses an enhancer duplication of 91 bp identical to that of a previously characterized polyomavirus mutant, PyNB11/1. We have demonstrated that this enhancer duplication gives rise at its junction to a novel recognition motif for the transcriptional factor NF-1 (M. Caruso, C. Iacobini, C. Passananti, A. Felsani, and P. Amati, EMBO J. 9:947-955, 1990). The regulatory region PyMB3 virus recombined in a wild-type genome context maintains the mutant phenotype. The other two types of mutants, one with a 30-bp enhancer duplication (e.g., PyMB40) and one with a wild-type enhancer structure (e.g., PyMB27), possess two similar but distinct 6-bp deletions in the same region of the VP1 coding gene. In both cases, the ability to replicate in undifferentiated C2 myoblasts is strictly correlated to the mutation in the VPI coding region
A new species of the genus Crisilla Monterosato, 1917 from the Mediterranean Sea (Gastropoda: Rissoidae)
No full textA new Mediterranean species of the genus Crisilla Monterosato, 1917 (Rissooidea, Rissoidae) is described:
Crisilla hiera n. sp. All known specimens are empty shells retrieved from a sample of bioclastic sand collected
in a submarine cave at Marettimo Island (type locality). It is compared with the most similar congeners
from the Mediterranean Sea, such as Crisilla beniamina (Monterosato 1884), C. aartseni (Verduin
1984), C. ramosorum Oliver, Templado & Kersting, 2012, C. didyme Amati & Oliverio, 2020 and Crisilla sp.
(Romani et al., 2018), and from the Eastern Atlantic Ocean, such as C. ugesae (Verduin, 1988) and C.
ugesae sensu Auctores. Crisilla didyme is first reported from a site different from the type locality, at Capo
Palinuro (southern Tyrrhenian Sea)
Influential users in Twitter: detection and evolution analysis
No full textIn this paper, we study how to detect the most influential users in the microblogging social network platform Twitter and their evolution over time. To this aim, we consider the Dynamic Retweet Graph (DRG) proposed in Amati et al. (2016) and partially analyzed in Amati et al. (IADIS Int J Comput Sci Inform Syst, 11(2) 2016), Amati et al. (2016). The model of the evolution of the Twitter social network is based here on the retweet relationship. In a DRGs, the last time a tweet has been retweeted we delete all the edges representing this tweet. In this way we model the decay of tweet life in the social platform. To detect the influential users, we consider the central nodes in the network with respect to the following centrality measures: degree, closeness, betweenness and PageRank-centrality. These measures have been widely studied in the static case and we analyze them on the sequence of DRG temporal graphs with special regard to the distribution of the 75% most central nodes. We derive the following results: (a) in all cases, applying the closeness measure results into many nodes with high centrality, so it is useless to detect influential users; (b) for all other measures, almost all nodes have null or very low centrality and (c) the number of vertices with significant centrality are often the same; (d) the above observations hold also for the cumulative retweet graph and, (e) central nodes in the sequence of DRG temporal graphs have high centrality in cumulative graph
A numerical jet model for the prompt emission of gamma-ray bursts
No full textGamma-ray bursts (GRBs) are known to be highly collimated events, and are mostly detectable when they are seen on-axis or very nearly on-axis. However, GRBs can be seen from off-axis angles, and the recent detection of a short GRB associated with a gravitational wave event has conclusively shown such a scenario. The observer viewing angle plays an important role in the observable spectral shape and the energetic of such events. We present a numerical model that is based on the single-pulse approximation with emission from a top-hat jet and has been developed to investigate the effects of the observer viewing angle. We assume a conical jet parametrized by a radius Rjet, half-opening angle θjet, a comoving-frame emissivity law and an observer viewing angle θobs, and then study the effects for the conditions θobs < θjet and θobs > θjet. We present results considering a smoothly broken power-law emissivity law in jet comoving frame, albeit the model implementation easily allows to consider other emissivity laws. We find that the relation E^{
m i}_{
m p}propto E_{
m iso}^{0.5} (Amati relation) is naturally obtained from pure relativistic kinematic when Gamma gtrsim 10 and θobs < θjet; on the contrary, when θobs > θjet it results E^{
m i}_{
m p}propto E_{
m iso}^{0.25}. Using data from literature for a class of well-know sub-energetic GRBs, we show that their position in the E^{
m i}_{
m p}!-!E_{
m iso} plane is consistent with event observed off-axis. The presented model is developed as a module to be integrated in spectral fitting software package xspec and can be used by the scientific community
Revision of the Recent Alvania scabra (Philippi, 1844) complex (Mollusca, Gastropoda, Rissoidae) from the Mediterranean Sea with the description of a new species
No full textHerein we revise several Recent Mediterranean species of the rissoid genus Alvania Risso, 1826: Alvania scabra (Philippi,
1844), Alvania sculptilis (Monterosato, 1877), Alvania sororcula Granata-Grillo, 1877, Alvania lucinae Oberling, 1970,
Alvania josefoi Oliver & Templado, 2009 and Alvania scuderii Villari, 2017. They represent a rather homogeneous group
of morphologically similar species, referred to as the Alvania scabra complex, which includes also some other species
from the northeastern Atlantic. We designate a neotype for Rissoa scabra Philippi, 1844 and a lectotype for Rissoa
oranica Pallary, 1900 to stabilize the use of the names. Alvania oranica (Pallary, 1900) is confirmed as a synonym of
Alvania scabra (Philippi, 1844), and Alvania asperella (Granata-Grillo, 1877) is proposed as a synonym of Alvania
sororcula (Granata-Grillo, 1877) [new synonymy]. Finally, we describe one new Mediterranean species: Alvania pizzinii
Amati, Smriglio & Oliverio n. sp. from Levanzo Is., Sicily
Forme e spazi del ‘vissuto consolidato e temporaneo’: la comunità latinoamericana a Roma,
No full textIl testo traccia un profilo della comunità latinoamericana a Roma in relazione alle forme e alle modalità del vivere quotidiano: un quadro di riferimento che rivela due modalità di vivere lo spazio e la città: da un lato un vissuto consolidato e, dall'altro, un vissuto temporaneo e precario ai margini e dentro la città consolidat
Non-dimensional design approach for electrodynamic bearings
No full textElectrodynamic bearings (EDBs) are passive magnetic bearings that exploit the interaction between eddy currents developed in a rotating conductor and a static magnetic field to generate forces. Similar to other types of magnetic suspensions, EDBs provide contactless support, thus avoiding problems with lubrication, friction and wear. The most interesting aspect of EDBs is that levitation can be obtained by passive means, hence, no electronic equipment, such as power electronics or sensors, are necessary. Despite their promising characteristics, rotors running on EDBs are still lacking a design procedure; furthermore, at present the static behavior of a bearing can only be defined by means of finite element analyses. The aim of the present paper is to present a methodology that allows performing a first approximation design without resorting to detailed FE analyses. The methodology is based on the use of non-dimensional parameters, similar to the analysis of fluid bearings (Sommerfeld number). The non-dimensional quantities are derived using dimensional analysis, and contain the main geometrical and physical parameters determining the EDBs' performance. The relation between the non-dimensional quantities characterizing the static performance of the EDB is derived using FE simulations and is presented in the form of graph
Revision of the Recent Mediterranean species of Mitromorpha Carpenter, 1865 (Gastropoda, Conoidea, Mitromorphidae) with the description of seven new species.
No full textThe Mediterranean species of the genus Mitromorpha Carpenter, 1865 as currently conceived, are herein reviewed. The genus is represented in the Mediterranean Sea by eleven species, of which seven are here described as new, all included conservatively in the subgenus Mitrolumna Bucquoy, Dautzenberg & Dollfus, 1883: Mitromorpha (Mitrolumna) columbellaria (Scacchi, 1836), Mitromorpha (Mitrolumna) olivoidea (Cantraine, 1835), Mitromorpha (Mitrolumna) karpathoensis (Nordsieck, 1969), Mitromorpha (Mitrolumna) wilhelminae (van Aartsen, Menkhorst & Gittenberger, 1984), Mitromorpha (Mitrolumna) alyssae n. sp., Mitromorpha (Mitrolumna) bogii n. sp., Mitromorpha (Mitrolumna) cossyrae n. sp., Mitromorpha (Mitrolumna) nofronii n. sp., Mitromorpha (Mitrolumna) mariottinii n. sp., Mitromorpha (Mitrolumna) mifsudi n. sp., and Mitromorpha (Mitrolumna) tricolorata n. sp. Neotypes are designated for: Mitra columbellaria Scacchi, 1836, [currently Mitromorpha columbellaria (Scacchi, 1836) comb. nov.], and Mitrolumna algeriana Pallary, 1900 ex Monterosato ms. [currently Mitromorpha algeriana (Pallary, 1900) comb. nov.] considered as a synonym of Mitromorpha columbellaria (Scacchi, 1836). The latter is the oldest available name for the most common and widespread Mediterranean species of Mitromorpha. A lectotype is selected for Mitra leontocroma Brusina, 1866 [currently Mitromorpha leontocroma (Brusina, 1866) comb. nov.], previously considered as a junior synonym of Mitromorpha olivoidea (Cantraine, 1835) but here considered as a junior synonym of Mitromorpha columbellaria (Scacchi, 1836). Mitromorpha melitensis (Mifsud, 1993) is a synonym of Mitromorpha olivoidea (Cantraine, 1835). Mitromorpha mediterranea Mifsud, 2001 is a synonym of Mitromorpha columbellaria (Scacchi, 1836)
Benthonellania megan Amati & Giulio & Oliverio 2022, n. sp.
No full textBenthonellania megan n. sp. (Figs 18 A-K; 19F-H; 25G; 26L; Tables 1; 2) urn:lsid:zoobank.org:act: 9B36A331-6E3D-48ED-8B90-31C7D64BB919 TYPE MATERIAL. — Holotype. Marquesas • 1 dd (height 2.7 mm, width 1.6 mm, Figs 18 A-E; 19F-H); Fatu Hiva, MUSORSTOM 9 Stn DR1247; 10°34’S, 138°42’W; 1.IX.1997; 1150-1250 m depth; MNHN-IM-2000-37695. Paratypes. Marquesas • 5 dd; same locality data as holotype; MNHN-IM-2000-37696. TYPE LOCALITY. — Marquesas, Fatu Hiva, MUSORSTOM 9 Stn DR1247; 10°34’S, 138°42’W; 1150-1250 m depth. OTHER MATERIAL EXAMINED. — Australes • 1 dd; Rimatara, BENTHAUS Stn DW2021; 22°37’S, 152°49’W; 25.XI.2002; 1200-1226 m depth. DISTRIBUTION AND SYMPATRY. — The species is at present known from the South Pacific Ocean, at Marquesas (Fatu Hiva Island) and Australes (Rimatara), with only empty shells collected in 1150- 1250 m depth (Fig. 25G). Benthonellania megan n. sp. is sympatric with Benthonella boucheti n. sp. at the Marquesas (Fatu Hiva Island) and Australes (Rimatara); with Benthonella communis n. sp. at the Australes (Rimatara); with Benthonellania bouteti n. sp. at the Australes (Rimatara); with Benthonellania tarava n. sp. at the Australes (Rimatara); with Benthonellania lozoueti n. sp. at the Marquesas (Fatu Hiva Island); with Benthonellania alis n. sp. at the Australes (Rimatara) (Table 2). ETYMOLOGY. — Dedicated to Megan Zampa, granddaughter of one of the authors (B. Amati). DESCRIPTION OF HOLOTYPE Shell (Figs 18 A-C; 19F-H) Small for the genus, height 2.7 mm, width 1.6 mm, height/ width ratio 1.687, pretty solid, ovate-conical. Protoconch (Figs 18D, E; 19G, H) Multispiral, acute of 2.5 whorls, height 0.40 mm, nucleus diameter 0.095 mm, first half whorl diameter 0.162 mm, maximum diameter 0.437 mm; (protoconch I in poor condition), protoconch II with two fine spiral keels, the lower larger, a fine cordlet of microtubercles in the subsutural area. Microtubercles spread over the entire surface (Fig. 19G, H). Protoconch-teleoconch boundary barely visible, sinuous. Teleoconch Of c. 3.5 convex whorls, suture canaliculate, crowned by small tubercles at tips of axial ribs. Height last whorl 1.75 mm, height/height last whorl ratio 1.542. Axial sculpture of 16 curved, slightly opisthocline ribs on last whorl, slightly narrower than interspaces, abruptly interrupted on the suture line. Spiral sculpture of 3 very weak fine cordlets on the base. Microsculpture of only growth striae (Fig. 19H). Umbilical chink absent. Aperture pyriform, large, height 1.1 mm, height/height aperture ratio 2.454, peristome continuous, varix absent (outer lip broken). Columella arcuate, simple. Colour Coloration of teleoconch translucent white, protoconch orange. Operculum and soft parts Unknown. VARIABILITY Species not very variable (See Table 1 and Appendix 11). REMARKS All the examined specimens have a broken peristome (presence/absence of lip thickening not observable). B. tarava n. sp. differs from B. megan n. sp. in its larger size height 2.92-3.75 mm vs heigh 2.40-2.70 mm in B. megan n. sp., higher height/width ratio 1.859 -1.807 vs 1.662 in B. megan; more whorls 4-4.65 vs 3.20-3.50 in B. megan n. sp., less numerous axial ribs on the last whorl 11-14 (mean 12.6) vs 14-19 (mean 16.5) in B. megan n. sp., and its more slender protoconch with two fine spiral cordlets, with a large smooth median area, and a fine spiral cordlet below the abapical cordlets vs two fine spiral cordlets, the lower larger, a fine cordlet of microtubercles in the subsutural area and microtubercles over the entire surface in B. megan n. sp.Published as part of Amati, Bruno, Giulio, Andrea Di & Oliverio, Marco, 2022, Deep-water Rissoidae of the genera Benthonella Dall, 1889 and Benthonellania Lozouet, 1990 (Gastropoda, Caenogastropoda, Rissooidea) from French Polynesia, pp. 335-389 in Zoosystema 44 (12) on pages 366-368, DOI: 10.5252/zoosystema2022v44a12, http://zenodo.org/record/679484
Mitromorpha (Mitrolumna) alyssae Amati, Smriglio & Oliverio, 2015, n. sp.
No full textMitromorpha (Mitrolumna) alyssae n. sp. (Figs 17; 18 A–E; 27 F; 28 F) Type material. Holotype, type locality, (H 7.3 mm, W 3.45 mm) (Fig. 18 A–C; 28 F) (MNHN IM- 2000-27707); paratypes: 9 sh (5 adults and 4 juv.: BA) type locality, 2 sh (MO), all from the type locality; 4 sh, Salina Is., - 46 m bioclastic sand, 2002 (CS). Type locality. Salina Is., Aeolian Islands, Italy, - 35 m. Etymology. Dedicated to Alyssa Rocchino, granddaugther of one of the authors (B. Amati). Distribution and habitat. Found so far only from the type locality area, Salina Is., in the southern Tyrrhenian Sea. Recent. Empty shells in bioclastic sands, - 35 m (cave) and - 46 m. Found sympatric with M. columbellaria and M. karpathoensis. Description. (in parentheses the data of the holotype) Shell of medium size for the genus (Figs 18 A–E; 27 F), height 7–7.95 (7.3 mm), width 3.3–3.6 (3.45 mm), solid, fusiform, biconic, slender, H/W= 2.028–2.208 (2.115). Protoconch paucispiral (Fig. 28 F) shiny, of 1.3–1.35 (1.35) convex whorl, d 0.20–0.225 (0.20 mm), Do 0.40–0.45 (0.40 mm), DM 0.55 mm, h 0.45 mm. sculptured by many densely arranged microgranules. Protoconchteleoconch boundary well marked, flexuose, opisthocline. Teleoconch of 5–5.5 (5) slightly convex whorls. Sculpture starting with 3 (3) strong spiral cordlets crossed by 12 (12) equally strong axial ribs on the first whorl. Additional spiral cordlets between the adapical ones, and between the suprasutural one and the suture. Last whorl sculptured over the entire surface by 22–25 (24) spiral cordlets, of which 7–10 (8) above the aperture. First 4 abapical spirals, rather strong, broader than the interspaces, lower 9 thinner, flat, those on the base stronger and more spaced. Axial ribs (13–16) present only on the first 3.5 whorls of all shells, producing rounded nodules at the intersection with the spirals and quadrangolar interspaces. Two columellar folds, the posterior larger and frequently bifid on the outer tip (Fig. 6 D). Growth lines visible over the entire surface. Outer lip sharp, thickened internally with 10 (10) small denticles, the second or third posterior more pronounced. Anal sinus shallow. Siphonal canal short, and wide. Coloration brown in the background, with subsutural lighter band, and periphery with small darker blotches and whitish rounded spots. Tubercles lighter than the background. Outer lip lighter, with occasional darker stripes posteriorly. Soft parts unknown. Remarks. M. alyssae n. sp. is similar to M. olivoidea in the chromatic pattern with a brown background and dark and light blotches in the peripheral area, but the blotches are larger, darker and more numerous. M. alyssae lives probably in shallower habitat (empty shells in 35–46 m v. 60 –170 m of M. olivoidea), and differs also in having less spirals on the last whorl (22–25 v. 34 –39 of M. olivoidea) and a coarser sculpture in the first whorls. M. columbellaria has a different chromatic pattern, usually monochrome, and less spirals above the aperture (4–6 v. 7–10 of M. alyssae n. sp.). M. alyssae n. sp. differs from M. karpathoensis (including all morphs), in its less brilliant and colorful chromatic pattern, in having less spirals on the last whorl (22–25 v. 30–40 in karpathoensis) and above the aperture (7– 10 v. 3–4 in karpathoensis). The morphs A and B of karpathoensis have less evident spiral and axial sculpture.Published as part of Amati, Bruno, Smriglio, Carlo & Oliverio, Marco, 2015, Revision of the Recent Mediterranean species of Mitromorpha Carpenter, 1865 (Gastropoda, Conoidea, Mitromorphidae) with the description of seven new species, pp. 151-195 in Zootaxa 3931 (2) on pages 172-174, DOI: 10.11646/zootaxa.3931.2.1, http://zenodo.org/record/23842
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