135,483 research outputs found
Mechanisms controlling Pax6 isoform expression in the retina have been conserved between teleosts and mammals
No full textAbstractThe Pax6 gene plays several roles in retinal development, including control of cell proliferation, maintenance of the retinogenic potential of progenitor cells, and cell fate specification. Emerging evidence suggests that these different aspects of Pax6 gene function are mediated by different isoforms of the Pax6 protein; however, relatively little is known about the spatiotemporal expression of Pax6 isoforms in the vertebrate retina. Using bacterial artificial chromosome (BAC) technology, we modified a zebrafish Pax6a BAC such that we could distinguish paired-containing Pax6a transcripts from paired-less Pax6a transcripts. In the zebrafish, the spatial and temporal onset of expression of these transcripts suggests that the paired-less isoform is involved in the cell fate decision leading to the generation of amacrine cells; however, because of limitations associated with transient transgenic analysis, it was not feasible to establish whether this promoter was active in all amacrine cells or in a specific population of amacrine cells. By making mice transgenic for the zebrafish Pax6a BAC reporter transgene, we were able to show that paired-containing and paired-less Pax6a transcripts were differentially expressed in amacrine subpopulations. Our study also directly demonstrates the functional conservation of the regulatory mechanisms governing Pax6 transcription in teleosts and mammals
The dynamics of stochastic mono-molecular reaction systems in stochastic environments
No full textWe study the stochastic dynamics of a system of interacting species in a stochastic environment by means of a continuous-time Markov chain with transition rates depending on the state of the environment. Models of gene regulation in systems biology take this form. We characterise the finite-time distribution of the Markov chain, provide conditions for ergodicity, and characterise the stationary distribution (when it exists) as a mixture of Poisson distributions. The mixture measure is uniquely identified as the law of a fixed point of a stochastic recurrence equation. This recursion is crucial for statistical computation of moments and other distributional features
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Is the fish-hook effect in hydrocyclones a real phenomenon?
No full textAlthough the fish-hook effect has been reported by many for a very long time, scientists and practitioners
alike share contradictory opinions about this phenomenon. While some believe that it is of physical origin,
others opine that it is the result of measurement errors. This article investigates the possibility that the
fish-hook effect could indeed be measurement error related. Since all the experimental errors are embedded
in the raw size distribution measurements, the paper first lays down the steps that lead to estimation of the
partition function and confidence bounds, which are seldom reported in hydrocyclone literature, from the
errors associated with the experimental size distribution measurements. Using several data sets generated
using a 100 mm diameter hydrocyclone operating under controlled dilute to dense regimes, careful analysis
of the partition functions following the developed methodology yields unambiguous evidence that the
fish-hook effect is a real physical phenomenon. An attempt is also made to reunite some of the major contradictory
views behind the existence of the fish-hook based on sound statistical arguments
Groundwater and surface water data of Ganga Delta
No full textThe present study attempts to characterize the strontium signatures and exchanges between surface water and multi-depth groundwater in and around the tropical, Himalayan Ganga River mega-delta. This work is an amalgamation of previously published datasets and newly collected data from surface and groundwater reservoirs which are predicted as potential strontium sources. Rainwater, seawater, river water, estuarine water and groundwater are considered as the different reservoirs within the delta where continuous cycling between the surface and subsurface waters is clearly observable. Strontium concentration data along with other solute geochemistry such as calcium, magnesium and salinity are reviewed from various previous literatures. Additionally, groundwater is sampled and analysed in two distinctly different parts of the delta. The first cluster of groundwater stations is distributed methodically in Nadia District, located inland in the northern part of the delta. The second set of groundwater stations is placed in 5 locations on the Bakkhali Island of Sundarbans, situated at the southern end. In total 13 observation wells, categorized into four depth ranges ̶ D1 (14 to 25 m bgl), D2 (30 to 50 m bgl), D3 (115 m bgl), and D4 (333 m bgl) and 2 monitoring wells were installed. D1 and D2 wells are installed in each of the five locations. D3 has two wells at locations B and D while D4 has only one well for observation at location A. This aids in a spatial understanding of the study area. For a similar reason, the assimilated groundwater data is geographically classified into Eastern and Western Bengal Basin whereas hydrostratigraphically, following our previous continuing study by Chakraborty et al., 2022 it is categorized under Type-I, Type-II and Type-III aquifers. Depth-wise variation is furthermore scrutinized to identify varying surface, shallow surface and deeper subsurface processes prevailing in both inland and coastal aquifers. Again, data variability from coastal reservoirs to further inland areas is used to demarcate a spatial change in the dominant hydrogeochemical process controlling water geochemistry and strontium evolution in the delta
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
Estimating Intra Country and Cross Country Purchasing Power Parities from Household Expenditure Data Using Single Equation and Complete Demand Systems Approach: India and Vietnam
No full textThis study departs from the previous literature on purchasing power parity (PPP) by proposing a demand system based methodology for calculating the PPP that takes account of consumer preferences and allows for the substitution effect of price changes. The methodology is applied to provide evidence on PPP between the Indian Rupee and the Vietnamese Dong. The study is conducted within a framework that allows for regional variation in preferences and price changes both inside the country and between countries and proposes and applies a methodology for constructing prices from unit values after adjusting them for quality and demographic effects. Using these prices the intra-country PPPs for India and Vietnam are calculated using the single equation (Engel curve based) procedure of Coondoo, Majumder and Chattopadhyay (2011). The cross country PPPs are calculated between sectors and across expenditure classes, apart from PPP at aggregate country to country level, using both the single equation and system based procedures. The paper contains evidence that the incorporation of price effects leads to a significant change in the PPP rates obtained from using cross section data (single equation procedure) ignoring price changes. The demand system based methodology yields PPP rates that are consistent with those obtained from conventional procedures such as the CPD method, yields standard errors of the PPPs and has the additional advantage of testing for invariance of inter-country PPP across expenditure classes. The disaggregated PPP rates question the conventional practice of using a single economy wide PPP in inequality and poverty comparisons.Purchasing Power Parity, QAIDS, CPD method, Spatial Prices, TCLI.
Pelossus indicus Majumder & Ghate & Chandra 2022, sp. nov
No full textPelossus indicus sp. nov (Figs. 1–2) Type material: HOLOTYPE: ♂, ‘ India: Chhattisgarh / Kabirdham / Bhoramdev Wildlife Sanctuary / Sakri River / 22 ° 05’40.9” N and 81 ° 09’52.1” E, Alt. 427m / 30. ix. 2013 / A. Raha & Party Coll. // HOLOTYPE / Pelossus indicus sp. nov. / des. Majumder, Ghate, Chandra 2021’ (red label) (ZSI). TWO PARATYPES (white locality label, pink label: “ PARATYPE / other data ditto as holotype) Description. Measurements (in mm): Holotype, ♂: body length 11 (from vertex to tip of elytra), width 3 (at the base of elytra); elytra length 7; pronotum length 3, width 2; antenna length 20. Small, elongate beetle; body colour dark brown to blackish brown at places (head, pronotum and femora) with fine golden or grey pubescence all over the body. Head: Sub vertical; frons small, sub squarish, depressed in middle, little raised at apex, warty, impressed with median, shining longitudinal sulcus covered with greyish golden pubescence; clypeus small, brownish, separated from the frons with a depressed triangular impression; mandibles moderately robust; vertex warty, covered with greyish golden pubescence (Fig. 1 D); antennal supports distinctly raised with their tips slightly angulated, with prominent median smooth sulcus in between; eyes very large, coarsely facetted, slightly emarginated, occupying major portion of head laterally (Fig. 1 J). Antennae long, almost twice the length of the body, brownish black throughout, with greyish pubescence; segment I (scape) strongly thickened, less pubescent and warty, warts sharp at apex, II gradually thickened in apical region, densely pubescent, nearly half of segment I, III segment almost double in length of I but little shorter than IV, remaining segments nearly equal in length, segments VII onwards thinner (Figs. 1 A - C). Thorax: Prothorax broader than head, slightly longer than broad, brownish black with golden pubescence, pubescence more on disc less on lateral margins; pronotal surface rough, granulated, disc depressed, lateral margin very finely curved with some indistinct, blunt tubercles. Width of prothorax distinctly less than width at humeral angles of elytra (Figs. 1 A, E). Elytra elongate, about two and half times the width at humerus, gradually narrowing towards apex; apex of each elytron individually rounded, densely pubescent; each elytron finely punctured, with very small punctures throughout and few large punctures in basal region, punctures sparse in apical region; overall punctures often obscured by pubescence; basal region of elytra around scutellum slightly elevated; scutellum small, transverse and V shaped, black; one moderately prominent longitudinal ridge or costa, on each side of suture, starting from just behind humerus but falling short of apex; humeral angles rounded (Fig. 1 F). Thorax ventrally dark brown to black, glossy due to sparse pubescence; procoxal cavities open, prosternal process very narrow, visible part small, triangular, with broad tip, depressed in middle; mesocoxal cavities open to epimera, mesosternal process triangular, its apical part with shallow channel in middle; metasternum broad, with median sulcus in posterior two third region (Fig. 1 G). Legs of moderate length, distinctly compressed, hind femora not extending to apex of abdomen. All femora strongly clavate, all tibia slender, subequal to femora in length, with usual apical spine; tarsus with first tarsal segment much longer, nearly double in length than that of remaining segments united; claws divaricate (Fig. 1 B). Male genitalia: Median lobe longer than tegmen; apical portion of median lobe much smaller than median struts; apex of median lobe very blunt, rounded. Ring portion of tegmen ‘V-shaped. Paramere lobes of medium length, with broad, rounded tip, very close to each other, almost overlapping, with sparse setae; endophallus long, with pair of laminar sclerites seen in the other species of this genus (Fig.2). Etymology: The species name indicus is derived from the country of occurrence: India. Distribution: India; so far known only from type locality: Chhattisgarh; female unknown Differential diagnosis and discussion: The genus Pelossus Thomson, 1864 was founded on Corethrogaster ruber Thomson, 1858. The original description of the genus is brief and is in French. The characters of our specimen matched with the original description of the genus as well with some recently described species under Pelossus, as discussed below. These males collected from Chhattisgarh are different from the other known Asian species of the genus in having darker and slender body and with the elytra narrowed towards apex. Therefore, these males are described as a new species under the genus Pelossus and are compared with the other similar species. Five species of Pelossus are known from Asia, as listed in introduction. The new species Pelossus indicus is significantly different from all these five species in possessing dark brown to blackish brown body colour, as the other species are of lighter colouration; besides colouration, P. indicus sp. nov. also differs from the other Asian species in the shape of prothorax, elytral characters and the structure of the male genitalia. P. unicolor (Gressitt, 1951) [type locality W. Lichuan Dist., Hupeh province, China], which is recorded from China and Vietnam, is a smaller species (female holotype, 8 mm length, 2 mm breadth), with body colour reddish brown [as per the original description by Gressitt 1951] and the elytra are without any carinae or costae, so in both these characters it differs from P. indicus sp. nov. Additionally, considering the structure of male genitalia of P. unicolor that was subsequently described and illustrated by Yokoi et al. (2016), based on a Vietnamese specimen, it appears that the lobes of parameres in P. unicolor are of uniform breadth from base to apex while those are club like in P. indicus sp. nov. The species P. kalimantanus Yokoi, Makihara & Noerdjito, 2016 (type locality East Kalimantan, Indonesia) is different in having ochraceous body colour and elytra with dark blackish apical region but these characters are absent in P. indicus sp. nov.; in addition the male genitalia in P. kalimantanus are also different, especially because the lobes of parameres are divergent in this species while those are very close to each other in P. indicus sp. nov.. The species P. wakabayashii Yokoi, Makihara & Noerdjito, 2016 (type locality Kalimantan Timur, Indonesia), differs from P. indicus sp. nov. in possessing testaceous body colour (as against blackish brown in P. indicus sp. nov.) and in having pronotum more rounded at sides; besides the male genitalia in P. wakabayashi are also very different with sinuate median struts and divergent lobes of parameres while the median struts in P. indicus sp. nov. are not sinuous and paramere lobes are very close, not divergent. The species P. maruyamai Niisato, 2017 (type locality Langkawi Is., West Malaysia) is similar in appearance but smaller (8.6 mm) and light brown than P. indicus sp. nov. (11 mm, blackish brown); further in P. maruyamai the elytral costae are indistinct while in P. indicus sp. nov. the costae are distinct; in addition, the median struts are also distinctly different in both the species. In the recently described species, Pelossus philippinensis Vives, 2018 (type locality N. Luzon, Abra Province, Philippines), the body colour is brown, prothorax is evenly rounded at sides, the elytra are parallel sided for most of their length and only narrowed in apical region, possess two costae per elytron, median struts are sinuate, the lobes of the parameres are gently rounded and possess sparse setae (Vives, 2018) whereas in P. indicus sp. nov. body colour is blackish brown, the prothorax is nearly parallel sided and not evenly rounded, the elytra are narrowed slightly beyond middle and there is a single costa per elytron, the median struts are not sinuate, shape of the tegmen is very different and the lobes of parameres are more broadly rounded. In addition, P. philippinensis appears robust and is a slightly longer species (length 12 mm) as opposed to slender and smaller P. indicus sp. nov. (length 11 mm). There are many species of Pelossus in the African Region but, as pointed out by Yokoi et al. (2016), the Asian species differ from all those in possessing mesocoxal cavities open, at least narrowly, to epimera. Hence it is not necessary to compare Pelossus indicus sp. nov. with the African species; however, it may be pointed out here that Pelossus costatus (Adlbauer 2012) [described as Lygrus costatus Adlbauer, 2012; length 8.5 to 11 mm, type locality Zambia] appears quite similar in colouration and general structure but here the antennal scape is smooth, as against very rough, and elytra are more parallel sided than those of P. indicus sp. nov. Similarly, P. becki Adlbauer, 2015 (type locality Aethiopia) is also a dark brown species but is also very large at 15 mm (length) while P. similis Adlbauer, 2015 (type locality Zambia) is a smaller (length 7–8 mm), yellow brown species and so both are significantly different from P. indicus sp. nov. (see Adlbauer 2015).Published as part of Majumder, Amitava, Ghate, Hemant V. & Chandra, Kailash, 2022, First report of the genus Pelossus Thomson, 1864 (Cerambycidae: Cerambycinae Pelossini) from India with description of a new species, pp. 593-599 in Zootaxa 5105 (4) on pages 594-598, DOI: 10.11646/zootaxa.5105.4.8, http://zenodo.org/record/633391
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
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