304 research outputs found
Common effect of chemical and external pressures on the magnetic properties of RCoPO (R = La, Pr, Nd, Sm). II.
No full textWe investigate the direct correspondence between Co band ferromagnetism and structural parameters in the pnictide oxides RCoPO for different rare-earth ions (R = La, Pr, Nd, Sm) by means of muon-spin spectroscopy and ab initio calculations, complementing our results published previously [G. Prando et al., Common effect of chemical and external pressures on the magnetic properties of RCoPO (R = La, Pr), Phys. Rev. B 87, 064401 (2013)]. We find that both the transition temperature to the ferromagnetic phase T-C and the volume of the crystallographic unit cell V are conveniently tuned by the R ionic radius and/or external pressure. We report a linear correlation between T-C and V and our ab initio calculations unambiguously demonstrate a full equivalence of chemical and external pressures. As such, we show that R ions influence the ferromagnetic phase only via the induced structural shrinkage without involving any active role from the electronic f degrees of freedom, which are only giving a sizable magnetic contribution at much lower temperatures
Iron-based superconductors: tales from the nuclei
No full textHigh-temperature superconductivity in Fe-based pnictides and chalcogenides has been one of the most significant recent discoveries in condensed matter physics and has attracted remarkable attention in the last decade. These materials are characterized by a complex fermiology and, as a result, feature a wide range of electronic properties as a function of different tuning parameters such as chemical doping, temperature and pressure. Along the path towards the comprehension of the physical mechanisms underlying this rich phenomenology, nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) have played a role of capital importance that we review in this work. In particular, we address how NMR has contributed to the current understanding of the main regions of the electronic phase diagram of Fe-based pnictides, that is, the—sometimes coexisting—antiferromagnetic spin-density wave and superconducting states. We evidence the unique capability of NMR as local-probe technique of investigating the effect of quenched disorder and chemical impurities. Then, we review the NMR signatures of low-frequency fluctuations associated with the development of electronic nematicity as well as with the motion of superconducting flux lines. Finally, we discuss recent contributions of NMR and NQR which evidence an intrinsically inhomogeneous electronic charge distribution as well as an orbitally-selective behaviour
Common effect of chemical and external pressures on the magnetic properties ofRCoPO (R=La,Pr,Nd,Sm). II
No full textWe investigate the direct correspondence between Co band ferromagnetism and structural parameters in the
pnictide oxides RCoPO for different rare-earth ions (R = La, Pr, Nd, Sm) by means of muon-spin spectroscopy
and ab initio calculations, complementing our results published previously [G. Prando et al., Common effect of
chemical and external pressures on the magnetic properties of RCoPO (R = La, Pr), Phys. Rev. B 87, 064401
(2013)]. We find that both the transition temperature to the ferromagnetic phase TC and the volume of the
crystallographic unit cell V are conveniently tuned by the R ionic radius and/or external pressure. We report a
linear correlation between TC and V and our ab initio calculations unambiguously demonstrate a full equivalence
of chemical and external pressures. As such, we show that R ions influence the ferromagnetic phase only via the
induced structural shrinkage without involving any active role from the electronic f degrees of freedom, which
are only giving a sizable magnetic contribution at much lower temperatures
The ESW of Wikidata: Exploratory search workflows on Knowledge Graphs
No full textExploratory search on Knowledge Graphs (KGs) arises when a user needs to understand and extract insights from an unfamiliar KG. In these exploratory sessions, the users issue a series of queries to identify relevant portions of the KG that can answer their questions, with each query answer informing the formulation of the next query. Despite the widespread adoption of KGs, the needs of current KG exploration use cases are not well understood. This work presents the “Exploratory Search Workflows” (ESW) collection focusing on real-world exploration sessions of an open-domain KG, Wikidata, conducted by 57 M.Sc. Computer Engineering students in two advanced Graph Database course editions. This resource includes 234 real exploratory workflows, each containing an average of 45 SPARQL queries and reference workflows that serve as gold-standard solutions to the proposed tasks. The ESW collection is also available as an RDF graph and accessible via a public SPARQL endpoint. It allows for analysis of real user sessions, understanding query evolution and complexity, and serves as the first query benchmark for KG management systems for exploratory search
A view from inside iron-based superconductors
No full textMuon spin spectroscopy is one of the most powerful tools to investigate the microscopic properties of superconductors. In this paper, an overview on some of the main achievements obtained by this technique in iron-based superconductors (IBS) are presented. It is shown how the muons allow to probe the whole phase diagram of IBS, from the magnetic to the superconducting phase, along with their sensitivity to unravel the modifications of the magnetic and the superconducting order parameters, as the phase diagram is spanned either by charge doping, by an external pressure or by introducing magnetic and non-magnetic impurities. Moreover, it is highlighted that the muons are unique probes for the study of the nanoscopic coexistence between magnetism and superconductivity taking place at the crossover between the two ground-states
Relationship between glutathione and sorbitol in erythrocytes from diabetic patients.
No full textRed blood cell (RBC) concentrations of sorbitol and reduced glutathione (GSH) were evaluated in 29 type II diabetic subjects and eight normal controls. In erythrocytes from diabetic subjects, sorbitol levels were higher (18.7 ± 1.33 v 11.2 ± 0.7 nmol/g hemoglobin [Hb], P < .001) and GSH levels were lower (5.48 ± 0.19 v 8.33 ± 0.24 μmol/g Hb, P < .01) than in nondiabetics. RBC sorbitol levels were positively correlated with fasting blood glucose (r = .57, P < .001) but not with HbA(1c) (r = .16, P = NS). RBC GSH levels showed a negative correlation with fasting blood glucose (r = - .35, P < .05) and with HbA(1c) (r = -.34, P < .05) and a significant negative correlation with RBC sorbitol levels (r = -.62, P < .001). Stepwise regression analysis highlighted the fact that the hyperglycemia-dependent increase in RBC sorbitol was significantly influenced by GSH concentrations (partial F = 14.6, P < .001). These data suggest the hypothesis that the hyperglycemia-induced enhanced activity of the polyol pathway leads to GSH depletion and, in turn, GSH depletion, reducing the glycolytic flux to pyruvate, enhances the rate of glucose metabolism through the polyol pathway. The overall effect is a progressive worsening of metabolic pseudohypoxia and depletion of GSH, resulting in lower defense against oxidative stress
Propetes sakakibara Prando & Gonçalves & Takiya 2017, sp. nov.
No full textPropetes sakakibara sp. nov. (Figs 1–4, 9–15) Length (mm). Males 13.0 – 15.0. Diagnosis. Connective anterior margin straight, without median lobe (Fig. 11). Aedeagus symmetrical; shaft shorter than atrial process; pair of atrial processes, each trifurcate, with two dorsal rami subequal in length with apices distant from each other for, at most, length of one ramus, and ventral ramus with length approximately one third of whole process length (Figs 12–13). External morphology. External morphological characters as in generic description (Young 1968: 204‒205). Color (holotype). Dark-brown. Crown, in dorsal view, with two small pale yellow maculae near posterior margin (Fig. 1). Face, in ventral view, dark-brown with two pale yellow maculae on dorsal portion of frons. Pronotum, in lateral view, reddish-brown (Fig. 2). Mesonotum dark-brown; scutellum with yellow apex. Forewing hyaline brown with dark-brown veins (Fig. 1). Legs dark-brown on dorsal surface and reddish-brown on lateral surface; hind tibia reddish-brown on basal half and pale yellow in part of apical half, apex black. Male genitalia. Pygofer moderately produced posteriorly; in lateral view, subrectangular; with transverse slightly membranous line dividing basal third from apical two-thirds; microsetae distributed on apical two-thirds; ventral margin with short basal rounded process; posterior margin obliquely truncate (Fig. 9). Subgenital plate, in lateral view, extending to approximately midlength of pygofer, in ventral view, subtriangular; ventral surface and external lateral margin with microsetae (Figs 9‒10). Connective, in dorsal view, approximately triangular; anterior margin straight, without median lobe; dorsal keel present (Fig. 11). Style extending slightly posterior to connective apex; apex truncate (Fig. 11). Aedeagus symmetrical; preatrium well developed; shaft, in lateral view, sigmoid, shorter than atrial processes, in caudoventral view, laterally compressed and with preapical region expanded; pair of atrial processes, each trifurcate, with two dorsal rami robust and subequal in length with apices distant from each other for, at most, length of one ramus, and ventral ramus slender and long with approximately one-third of whole process length (Figs 12‒15). Female. Unknown. Variation found in paratypes. Color. Crown brown with anterior half yellow and median longitudinal stripe pale yellow. Pronotum, in dorsal view, dark-brown with two small pale yellow maculae near anterior margin (Fig. 3). Thorax, in lateral view, with three distinct pale yellow maculae (Fig. 4). Male genitalia. Aedeagus with dorsal rami of atrial process, in lateral view, not subequal in length, and with apices close together (Figs 14‒15). Etymology. This species is named in honor of Dr. Albino M. Sakakibara (retired, Universidade Federal do Paraná) in recognition of his numerous contributions to Auchenorrhyncha taxonomy. The species epithet is treated as a noun in apposition. Notes. Propetes sakakibara sp. nov. resembles P. triquetra as follows: (1) crown and pronotum dark-brown or with few yellow maculae (Figs 1, 3); (2) aedeagus with shaft shorter than atrial processes (Figs 13, 15); and (3) aedeagal atrial processes, each trifurcate (Figs 13, 15). However, the new species differs from P. triquetra mainly by the shape of the connective and aedeagal atrial processes. In P. sakakibara sp. nov. the atrial process ventral ramus is long, measuring approximately one-third of whole process length and apices of dorsal rami are distant from each other for at most the length of one ramus (Figs 12, 14) and the connective does not have a median anterior lobe (Fig. 11). In P. triquetra the atrial processes ventral ramus is very small, measuring approximately one-tenth of whole process length and dorsal rami apices are distant from each other for a distance longer than the length of one ramus (Fig. 17‒18) and the connective has a median anterior lobe (Fig. 16). Material examined. BRASIL: Holotype male: 1 ♂ “ BRASIL, AM, Manaus, Rod. AM / 0 10, km50. ZF-2, km24, próximo/ à sede CPST, 02°35’S; 60°06’W.”; “ 4-5.iii.2011. 21-00:00h. Arm. luz/ fixa. J.A. Rafael; J.T. Camara;/ F.F. Xavier Filho leg”; INPA. Paratypes: 1 ♂ “[Brazil] Rio Branco-AC [Acre State]/ 12-Jan-2004 / Albuquerque, E. S. ”; “ Citrus 31”; DZUP. 1 ♂ “[Brazil] Rio Branco-AC [Acre State]/ 12-Jan-2004 / Albuquerque, E. S. ”; “ Citrus 78”; DZRJ. 1 ♂ “ BRASIL: Rondônia / 62 km S Ariquemes / Fazenda Rancho Grande / 165m. 10.53°S, 62.80°W / 19-29.ix.1996. B.Harris ”; LACM. 1 ♂ “ BRASIL: Rondonia / Porto Velho / 27-11-1979 / S. Camplell ”; INPA. 1 ♂ “ BRAZIL, RO 160-350m / vic. CAUCALANDIA[sic! Cacaulândia] / 10deg 32’S 62deg 48’W/ 28. OCT. 1991 / JOHN R. MACDONALD”; USNM. PERU: 2 ♂ “ PERU: Loreto Dept.,/ Exploranapo Campo n R./ Sucussari nr. R. Napo. / 12-19.III-1988 / J. E. Eger, coll.”; “collected at light”; FSCA. 1 ♂ “ PERU: Madre de Dios;/ Rio Tambopata Res; 30 air/ km. SW Pto.Maldonado, 290m. / 6-10.xi.1979 J.B. Heppner / subtropical moist forest”; “PT5”; USNM. VENEZUELA: 1 ♂ “VENEZUELA-TF/ Amazonas / San Carlos de/ Rio Negro / 7-13.xi.1982 ”; “ A. Chacom / G. Yapes Gil / col.”; MIZA. 1 ♂ “ Venezuela T.F/ Amazonas Dpt/ Rio Negro ”; “ S. Carlos de/ R. Negro 65m / 1°55’N 67°1’W ”; “ J. A. Clavijo / J. Demarmels / 4-14-III-84 ”; MIZA.Published as part of Prando, Jádila Santos, Gonçalves, Clayton Corrêa & Takiya, Daniela Maeda, 2017, On the wasp-mimicking sharpshooter genus Propetes Walker, 1851 (Hemiptera: Cicadellidae: Cicadellinae): description of a new species, proposal of a new synonymy, and distributional notes, pp. 165-175 in Zootaxa 4281 (1) on pages 167-168, DOI: 10.11646/zootaxa.4281.1.15, http://zenodo.org/record/81603
Portanus adenomari Felix & Quintas & Prando & Mejdalani 2020, sp. nov.
No full text<i>Portanus adenomari</i> sp. nov. <p>(Figs 1–21, 53)</p> <p> <b>Diagnosis.</b> Aedeagus with apical portion falciform, its apex with pair of very long, slender acute processes crossing each other medially, each process strongly curved posterodorsally, almost forming complete ring.</p> <p>Measurements (mm). Male holotype: total length 5.27; crown length 0.50; transocular width 1.22; interocular width 0.57; maximum pronotal width 1.23; forewing length 4.30. Male paratypes (n=4)/female paratypes (n=3): total length 4.45–5.02/4.85–5.46; crown length 0.42–0.48/0.48–0.51; transocular width 1.08–1.24/1.16–1.27; interocular width 0.52–0.56/0.56–0.60; maximum pronotal width 1.08–1.20/1.16–1.28; forewing length 3.60–4.10/3.95–4.60.</p> <p> <b>Description.</b> Head (Fig. 1) with median length of crown from 8/10 to 9/10 interocular width and 4/10 transocular width. Pronotum (Fig. 1) width similar to transocular width. Forewing (Fig. 2) with open inner anteapical cell; median cell approximately as long as outer one. Hind leg with femoral setal formula 2:2:1; length of basal tarsomere greater than combined length of two succeeding tarsomeres.</p> <p>Male terminalia. Pygofer (Fig. 3), in lateral view, short and slightly narrowed towards rounded apex; basidorsal margin with inner acute process, directed posterad and parallel to basal portion of anal tube; dorsal margin mostly concave, ending in short triangular projection; dorsal portion of pygofer with few long macrosetae forming oblique row, some short macrosetae near triangular projection. Valve (Fig. 4), in ventral view, approximately as long as broad, somewhat elliptical, posterior margin broadly rounded. Subgenital plate (Fig. 4), in ventral view, long, extending posteriorly beyond pygofer apex; dorsally curved; basal 1/3 with transverse membranous rounded line; apical 1/3 slightly expanded ventrally; apex rounded; ventral longitudinal row of four long macrosetae on median 1/3. Style (Fig. 5), in dorsal view, long and narrow, extending posteriorly well beyond connective apex; preapical lobe well produced; apical portion long and acute, slightly curved outwards, forming hook with preapical lobe, tiny dentiform subapical projection on outer margin. Connective (Fig. 5), in ventral view, Y-shaped; arms moderately long; anteromedian margin with small lobe; stalk very long, its apical portion broadened. Aedeagus (Figs 6, 7), in lateral view, long; basiventral portion with pair of short rounded lobes; shaft broadened basally, narrowing towards ventrally curved, broadened falciform apical portion; apex with pair of very long, slender acute processes crossing each other medially, each strongly curved posterodorsally, almost forming complete ring.</p> <p>Color. Dorsum (Fig. 1) mostly light yellowish-brown with ivory markings. Crown (Fig. 1) entirely light yellowish-brown except for pair of large, oblique elliptical brown spots on basal 1/2, attaining imaginary line between anterior eye angles; ocelli narrowly bordered by ivory. Eyes brown. Pronotum (Fig. 1) light brown with numerous small ivory spots; anterior portion with large brown areas. Mesonotum (Fig. 1) ivory with anterior pair of large brown spots; scutoscutellar suture brown. Forewing (Figs 1, 2, 8) translucent; veins mostly marked with alternating brown and ivory; costal margin with large, oblique irregular ivory macula bordered anteriorly and posteriorly by brown, located approximately opposite apex of clavus; basal veins of apical cells marked with brown; apical cells with large brown areas. Face (Figs 9, 10) pale yellow to brownish-yellow. Thoracic sclerites (Figs 8, 10) pale yellow laterally and ventrally. Legs (Fig. 8) pale yellow with some darker areas; apices of tarsi dark brown.</p> <p>Female terminalia. Sternite VII (Fig. 11), in ventral view, slightly concave on each side of short median lobe. “Internal” sternite VIII (Fig. 53), in dorsal view, with small sclerotized areas located between valvifers I. Pygofer (Fig. 12), in lateral view, moderately produced posteriorly; apex triangular; with long macrosetae distributed mostly on apical 1/2, shorter dorsally. Valvifer I, in lateral view, elliptical. Valvula I (Figs 13, 14), in lateral view, broadened dorsally on apical portion, narrowing gradually towards acute apex; dorsal sculptured area extending along distal 2/3 of blade, very narrow basally, formed mostly by rod-shaped elements; ventral sculptured area restricted to apical portion, formed by sparse scale-like processes; ventral interlocking device located on basal 1/3 of blade; in ventral view, basal portion of valvula I with slight outer lobe. Valvula II (Figs 15, 16), in lateral view, slightly expanded beyond basal curvature, distinctly narrowed towards apex; without preapical prominence; apical portion triangular; apex narrowly rounded; dorsal margin with about 30 teeth; most teeth subtriangular or obtuse dorsally, short, with anterior and posterior portions oblique; ventroapical margin serrate; blade surface with irregular granulate sculpturing, rod-shaped apically. Gonoplac (Fig. 17), in lateral view, abruptly expanded at median portion and then gradually narrowed posteriorly; apex obtuse; surface with numerous tiny denticuli apically and extending anteriorly along ventral margin, with few setae (about two or three) located apically.</p> <p>Intraspecific variation. Paratypes may show the following features: crown slightly orange with irregular dark areas and absence of pair of brown spots on basal 1/2 (Fig. 18); eyes silver; pronotum without anterior brown areas (Fig. 18); mesonotum mostly brown or with anterior pair of light yellowish-brown spots, anteromedian area with large irregular brown macula; subgenital plate with less than four long macrosetae on median 1/3.</p> <p> <b>Type material</b>. Brazil. Holotype: male, “Viçosa, MG [Minas Gerais State], Brasil \ Data 02/XII/1981 \ P. S. Fiuza F.” (DZRJ). Paratypes: one female, same data as holotype except “ 20/I/1982 ” (DZRJ); one male, “ Brasil, Paraná [State], Tibagi, \ P.E. do Guartelá, 1000m \ 24°33’47”S 50º15’26”W \ 23.II-06.III.2017 Malaise \ A.C. Domahovski, A. \ Martins & G. Melo legs.”; “DNA voucher: \ Entomologia, DZRJ \ ENT4757 ” (DZUP); six males, “ Brasil, Paraná [State], Tibagi, \ Parque Estadual do Guartelá, \ 24°33’47”S 50º15’26”W, 1000m, \ 23.II-06.III.2017, Malaise, \ A.C. Domahovski, A. Martins & \ G. Melo legs.” (DZUP); one male and one female, “ Brasil, Minas Gerais [State], Catas Altas,\ RPPN Santuário do Caraça,\ Campo de futebol, Trilha do Lobo \ Guará, 20º06’3.8”S, 43º29’10.1”W,\ 1240m, 17.iii.2015, Luz, AP, BMC,\ DMT, ALDF, CCG, FRF ” (DZRJ); one male, “ Brasil, Minas Gerais [State], Catas Altas,\ RPPN Santuário do Caraça, trilha\ p/cascatinha rib. Caraça,\ 20º06’23.5”S, 43º28’27.8”W,\ 1258m, 11-13.vi.2013, Malaise,\ ML Monné & JP Botero ” (MNRJ); one male and two females, “ Brasil, Maranhão [State], PARNA \ Chapada das Mesas, Riacho \ Sucuruiu, 7º7’6”S, 47º18’32”W,\ 240 m, 10-20.v.2014, Malaise, J.A.\ Rafael, F. Limeira-de-Oliveira, T. L.\ Rocha & G.A. Reis ” (CZMA).</p> <p> <b>Etymology.</b> The specific epithet, <i>adenomari</i>, is in honor of Prof. Dr. Adenomar Neves de Carvalho (Universidade Federal do Oeste do Pará, Brazil), who has greatly contributed to our knowledge of the Portanini.</p> <p> <b>Remarks.</b> <i>Portanus adenomari</i> <b>sp. nov.</b> is similar in color pattern and morphology of the male terminalia to the following species: <i>P. acerus</i> DeLong, 1976, <i>P. bifurcus</i> Carvalho & Cavichioli, 2017, <i>P. hasemani</i> (Baker, 1923), <i>P. lex</i> Kramer, 1964, <i>P. phoenicius</i> Souza & Takiya, 2014, <i>P. pictus</i> Carvalho & Cavichioli, 2001, <i>P. quadrinus</i> DeLong, 1976, <i>P. uhleri</i> Kramer, 1964, <i>P. xavantes</i> Carvalho & Cavichioli, 2001 (treated as a junior synonym of <i>P. uhleri</i> by Carvalho (2006) in his unpublished D.Sc. thesis), and <i>P. zacki</i> Freytag, 2017. They all have the crown almost uniformly brown, pronotum with numerous small pale spots, and mesonotum with anterior pair of large brown spots; forewing veins are marked with brown and white, the costal area has at least one large white macula on median portion, and the apical cells are almost entirely brown. Regarding the male terminalia, the pygofer is short and bears a small posterodorsal process, except in <i>P. bifurcus</i>, <i>P. lex</i>, and <i>P. zacki</i>; the aedeagus is curved at base and bears variable apical processes. However, in the new species, the processes are very long and slender, with acute apex, and cross each other medially, being each one strongly curved posterodorsally, almost forming a complete ring (Fig. 6). Unfortunately, an updated key to all species currently included in <i>Portanus</i> is not available.</p>Published as part of <i>Felix, Márcio, Quintas, Victor, Prando, Jádila Santos & Mejdalani, Gabriel, 2020, Portanini (Insecta, Hemiptera, Cicadellidae): morphology of female terminalia, first record of host plants, a new species of Portanus from Brazil, and taxonomic notes, pp. 569-581 in Zootaxa 4802 (3)</i> on pages 570-573, DOI: 10.11646/zootaxa.4802.3.11, <a href="http://zenodo.org/record/3907628">http://zenodo.org/record/3907628</a>
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