170,901 research outputs found
AKLT models with quantum spin glass ground states
No full textWe study AKLT models on locally treelike lattices of fixed connectivity and find that they exhibit a variety of ground states depending upon the spin, coordination, and global (graph) topology. We find (a) quantum paramagnetic or valence-bond solid ground states, (b) critical and ordered Neel states on bipartite infinite Cayley trees, and (c) critical and ordered quantum vector spin glass states on random graphs of fixed connectivity. We argue, in consonance with a previous analysis [C. R. Laumann, S. A. Parameswaran, and S. L. Sondhi, Phys. Rev. B 80, 144415 (2009)], that all phases are characterized by gaps to local excitations. The spin glass states we report arise from random long-ranged loops which frustrate Neel ordering despite the lack of randomness in the coupling strengths
Asteroschema sampadae Parameswaran & U, 2012, sp. nov.
No full textAsteroschema sampadae sp. nov. Materials examined. Holotype and paratype [CMLRE IO/SS/ECD/00021] collected on 20 th May, 2007 from 454m (Lat. 7? 10 ’N Long. 77? 19 ’E) during FORV Sagar Sampada Cruise No. 254. Diagnosis. Disc diameter (d.d.) about 18mm, arms about 380-450mm (21-23 times d.d.) Disc and arms covered by skin with small, scattered, distinctly conical epidermal ossicles on aboral side and minute spherical granular ossicles on oral side. Conical ossicles bearing a crown of minute spinous terminal projections. Dorsal ornamentation not closely packed anywhere on the body so that large parts of the disc and arms are overlaid by naked skin; but epidermal ossicles somewhat more dense on radial shields and at base of arms. Two arm spines from fourth arm segment; inner spine larger and approximately one third of the arm segment length, becoming twice the length of the arm segment in the middle of arm and bearing distinct thorny projections on the inner edge. The arm spines at the distal end of the arm are represented as small hook-shaped spines. Etymology. The species is named after the vessel FORV Sagar Sampada, on which it was collected. Type locality. Continental slope off the southern tip of India. Description of holotype. Disc diameter 18.8 mm; arms between 380 mm and 450 mm long (about 21-23 times d. d.); moderately excavate inter-radially and covered by skin which bears conical epidermal ossicles aborally (Fig. 2 B). Radial shields as narrow, elongate paired structures at base of arm; the shields widely separated running more or less parallel and extending a short distance beyond the disc proper; appearing to converge but not meeting centrally (Fig. 2 B). Genital slits wide and vertical (Fig. 2 C). Ossicles on aboral side of disc and around the genital slits are short and conical with a terminal projections at the tips (Fig. 2 F); distributed more densely on radial shields than the rest of the disc, but not very closely packed anywhere, so that large parts of the disc and arms are overlaid by naked skin (Fig. 2 A, B, D). Oral shield and oral plate covered by skin; embedded with minute spherical granular ossicles which are only visible when the dried skin is observed under a microscope. Oral plates elongate and extending into the mouth; bearing scattered, stout, domed granules on its vertical edge. Several, blunt and chisel shaped teeth; the lowermost tooth fragmented (Fig. 2 C). Arms not enlarged at the base; square in cross section, higher than wide at base (width 4.6 mm; height 4.9 mm); becoming more or less cylindrical and tapering distally. Aboral and lateral faces of the arm bearing conical epidermal ossicles similar to those on aboral side of the disc (Fig. 2 D). Ossicles more numerous towards the base of the arms (2–3 granules in 1mm) and becoming scarce at the tip of the arms. They decrease in size towards the ventro-lateral margins; being represented on the oral side of the arm, as microscopic spherical granular ossicles, as on oral face of the disc (Fig. 2 E). Dorsal arm plates absent. Lateral arm plates small and ventro-lateral in position; the plates of each side meeting mid-ventrally, but not fused together. Tentacles of the basal arm joints covered by a hollow sheath which projects from the tentacle pore. Second tentacle pore without any arm spines, a single spine present in the next two arm segments and two spines thereafter. Arm spines bluntly tapering, covered by a thin layer of skin and bearing minute thorny projections on the inner edge (Fig. 3 A, C, D). The inner arm spine always longer than the outer (Fig. 3 A). Arm spines increase in size along the arm; at about a third of the arm length, the inner arm spine attains a length of 5mm (as long as the arm width and twice as long as the arm joint), becoming distinctly cylindrical with welldefined thorny projections on the inner edge (Fig. 3 C, E). A mass of soft tissue adheres to the terminal projections, making the spine appear club-shaped (Fig. 3 A). The outer one reaching a maximum length of about 3 mm and remaining bluntly tapering (Fig. 2 D, F). Towards the distal third of the arm, both spines become progressively smaller and are represented as hooks, which do not have a lamina or regularly arranged perforations (Fig. 3 B, G). Colour in life, fawn; the disc relatively darker than arms with a greyish tinge; skin over the ossicles, tube-feet and tips of arm spines dark brown. Disc greyish and arms pale wheat in preserved specimen. Description of paratype. Disc diameter 17.6 mm; arms about 19–22 times d. d., arm width at base 4.2mm, height 5.2 mm. Disc is slightly more excavate than the holotype, with the central part of the disc a bit concave. This difference is likely to be because the mouth of the paratype is gaping open. Similar to holotype in all other characters. Biological association. Asteroschema sampadae was found in association with a gorgonacean of the family Primnoidae. Comparisons. Asteroschema sampadae resembles A. oligactes (Pallas, 1788) and A. tumidum Lyman, 1879 in the shape of the epidermal ossicles of the aboral side, but differs in the distribution of these ossicles, which is regular and close-set in these species but rather irregular and scattered in A. sampadae. The inner arm spines of A. oligactes is not much longer than the outer, whereas the inner arm spines of A. sampadae become twice as long as the outer towards the middle of the arm. In A. tumidum, the inner spine attains a length equaling one-third of the arm segment (2mm) and becomes rough ended and clubbed. While the shape of the inner spine of A. sampadae is similar to that of A. tumidum, the spines of A. sampadae are much longer, attaining twice the length of an arm segment (5mm). Moreover, A. sampadae is much larger than the type specimen of A. tumidum (8mm d. d., arms upto 135mm). While the minute granular epidermal ossicles on the oral side of A. sampadae are similar to those of A. flosculus Alcock, 1893 and A. nuttingii Verrill, 1899, the ossicles on the aboral side of these two species are closeset granular ossicles unlike A. sampadae. The arm spines of A. sampadae are similar in description to those of A. nuttingii, in which the inner spine is longest and largest, cylindrical and blunt, enlarged at the end with minute projections at the tip. A. nuttingii is the only other species to be described as having claw-like distal arm spines. A. sampadae is similar to A. tubiferum Matsumoto, 1915 with respect to the maximum size attained by the inner arm spines as well as the presence of a sheath around the basal tentacles. However, A. tubiferum possesses only coarse granular epidermal ossicles on the aboral side, while the aboral ossicles of A. sampadae are all distinctly conical. A. hemigymnum Matsumoto, 1915 also possesses a sheath around the basal tentacles, but the aboral ossicles of this species are close-set, fine, smooth granular ossicles, unlike the spaced conical ossicles of A. sampadae. A. sampadae differs greatly from A. lissum H. L. Clark, 1939 which has been reported from the nearby Maldives region, in its size as well as the shape of epidermal ossicles; A. lissum (8mm d.d., arms about 110mm) possesses only close-set, fine, low granular ossicles (40–60 in 1mm) on the aboral side. While both A. fastosum Koehler, 1904 and A. subfastosum Döderlein, 1930 have conical ossicles embedded in the aboral skin, A. sampadae differs from both in the nature of ossicles on the oral side, which are small, flattened conical ossicles in A. fastosum and close-set, smooth, hemispherical granular ossicles on A. subfastosum. In addition, the arm base of A. fastosum is distinctly enlarged, while that of A. sampadae is not. A comparison of A. sampadae with all species of Asteroschema having conical as well as granular epidermal ossicles, based on literature is presented in Table 2. Some species of the genus Ophiocreas Lyman, 1879 also have epidermal ossicles of various kinds and of these, Ophiocreas spinulosus Lyman, 1883 bears prominent blunt ‘spines’ or conical ossicles on the aboral skin. However, these are restricted to the radial shields and arm bases in O. sibogae, whereupon they are distributed evenly—a pair to each arm joint; while in the case of A. sampadae, the ossicles are irregularly scattered all over the aboral side of the disc and arms. Remarks. The most distinctive features of A. sampadae which separates it from other species are the shape and nature of the epidermal ossicles on the aboral and oral sides along with the large inner arm spines in the middle of the arms that are represented as hook-shaped structures at the distal part of the arm. The characteristic shape of the conical epidermal ossicles of the aboral side, crowned with short terminal projections is of significance.Published as part of Parameswaran, Usha V. & U, Abdul Jaleel K., 2012, Asteroschema sampadae (Ophiuroidea: Asteroschematinae), a new deep-sea brittle star from the continental slope off the southern tip of India, pp. 47-56 in Zootaxa 3269 on pages 50-55, DOI: 10.5281/zenodo.28079
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
An Aluminum Hydride That Functions like a Transition-Metal Catalyst
No full textThe reaction of [LAlH2] (L= HC(CMeNAr)(2), Ar= 2,6-iPr(2)C(6)H(3)) with MeOTf (Tf= SO2CF3) resulted in the formation of [LAlH(OTf)] (1) in high yield. The triflate substituent in 1 increases the positive charge at the aluminum center, which implies that 1 has a strong Lewis acidic character. The excellent catalytic activity of 1 for the hydroboration of organic compounds with carbonyl groups was investigated. Furthermore, it was shown that 1 effectively initiates the addition reaction of trimethylsilyl cyanide (TMSCN) to both aldehydes and ketones. Quantum mechanical calculations were carried out to explore the reaction mechanism
FIGURE 2 in Asteroschema sampadae (Ophiuroidea: Asteroschematinae), a new deep-sea brittle star from the continental slope off the southern tip of India
No full textFIGURE 2. Asteroschema sampadae sp. nov., A–C. live specimens, D–F. Holotype (CMLRE IO/SS/ECD/00021). A. entire organism, B. aboral view of disc, C. oral side of disc showing genital slits (arrow), D. holotype (CMLRE) conical epidermal ossicles on the aboral side of the arm (arrows), E. oral side of arm base, showing minute granular epidermal ossicles (arrow), F. conical epidermal ossicle from the aboral side of the arm, with terminal projections (arrow).Published as part of Parameswaran, Usha V. & U, Abdul Jaleel K., 2012, Asteroschema sampadae (Ophiuroidea: Asteroschematinae), a new deep-sea brittle star from the continental slope off the southern tip of India, pp. 47-56 in Zootaxa 3269 on page 51, DOI: 10.5281/zenodo.28079
A Multi-Language Comparison of Influences on Author Verification using Character N-Grams
No full textWe create a new multi-language corpus for author verification based on Wikipedia talkpages, and evaluate the influence that differences in topic and time have on character n-gram author profiles. Topic alignment between two texts is found to increase author verification precision, and an authors writing style is found to change over time, but not more significantly after 3 years than after 1 year.Information ArchitectureWISElectrical Engineering, Mathematics and Computer Scienc
Gauge fields, fermions and mass gaps in 6D brane worlds
No full textWe study fluctuations about axisymmetric warped brane solutions in 6D minimal gauged supergravity. Much of our analysis is general and could be applied to other scenarios. We focus on bulk sectors that could give rise to Standard Model gauge fields and charged matter. We reduce the dynamics to Schrodinger type equations plus physical boundary conditions, and obtain exact solutions for the Kaluza-Klein wave functions and discrete mass spectra. The power-law warping, as opposed to exponential in 5D, means that zero mode wave functions can be peaked on negative tension branes, but only at the price of localizing the whole Kaluza-Klein tower there. However, remarkably, the codimension two defects allow the Kaluza-Klein mass gap to remain finite even in the infinite volume limit. In principle, not only gravity, but Standard Model fields could 'feel' the extent of large extra dimensions, and still be described by an effective 4D theory. (C) 2007 Elsevier B.V. All rights reserved
A 0.12mm<sup>2</sup> Wien-Bridge Temperature Sensor with 0.1°C (3σ) Inaccuracy from -40°C to 180°C
No full text Resistor-based temperature sensors can achieve much higher resolution and energy efficiency than conventional BJT-based sensors [1], but they typically occupy more area (> 0.25 mm 2 ) and have lower operating temperatures (le 125 {circ} {C}) [2]-[4]. This work describes a 0.12mm 2 resistor-based sensor that uses a Wien-bridge (WB) filter to achieve 0.1 {circ} {C} (3 sigma) inaccuracy from - 40 {circ} {C} to 180 {circ} {C}. Compared to a state-of-the-art WB sensor [4], it occupies 6 × less area and achieves comparable relative accuracy over a 76% wider operating range. Session 10.3 Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
- …
