132,577 research outputs found
Chelonus ocellatus ALEXEEV 1971
No full textChelonus ocellatus ALEXEEV 1971 M a t e r i a l e x a m i n e d: Mazandaran province: Savadkooh, 1, July 2005. G e n e r a l d i s t r i b u t i o n Crimea, Middle Asia, Turkey (AYDOGDU & BEYARSLAN 2002).Published as part of Sakenin, H., Naderian, H., Samin, N., Rastegar, J., Tabari, M., Papp, J. & I, Northern, 2012, On a collection of Braconidae (Hymenoptera) from northern Iran, pp. 1319-1330 in Linzer biologische Beiträge 44 (2) on page 1323, DOI: 10.5281/zenodo.533526
Chelonus ocellatus ALEXEEV 1971
No full textChelonus ocellatus ALEXEEV 1971 M a t e r i a l: Mazandaran province: Savadkooh, Alasht (3), September 2003. G e n e r a l d i s t r i b u t i o n: Crimea,MiddleAsia, Turkey.Published as part of Ghahari, H., Fischer, M., Cetin, O., Beyarslan, A. & Ostovan, H., 2010, A contribution to the braconid wasps (Hymenoptera: Braconidae) from the forests of northern Iran, pp. 621-634 in Linzer biologische Beiträge 42 (1) on page 626, DOI: 10.5281/zenodo.533280
Income Distribution and Price Controls: Targeting a Social Safety Net During Economic Transition
No full textDuring the ongoing post-communist economic transitions, the relative well-being of many people is changing rapidly, and governments are not well positioned to accurately measure individual living standards. Under such circumstances, continued price controls over basic consumer goods within the state sector, and the associated queuing, can form a serviceable device for targeting poor people for subsidies. With a fixed-price state sector and free-price parallel markets, rich people might choose to avoid queues and shop in the free markets, while poor people would prefer to pay low nominal prices and queue in the state sector. The targeting of subsidies through queues, therefore, can be accomplished even if the government has no information on individual income or living standards. When the alternative to price controls is a poorly targeted explicit social safety net, the resource cost of queues might be more than compensated for by an improvement in the targeting of subsidies.price controls, tax evasion, queue-rationing, economic transition, income distribution
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
A generating functional approach to the Hubbard model
No full textThe method of generating functional, suggested for
conventional systems by Kadanoff and Baym, is generalized to the
case of strongly correlated systems, described by the Hubbard X
operators. The method has been applied to the Hubbard model with
arbitrary value U of the Coulomb on-site interaction. For the
electronic Green's function constructed for
Fermi-like X operators, an equation using variational
derivatives with respect to the fluctuating fields has been
derived and its multiplicative form has been determined. The
Green's function is characterized by two quantities: the self
energy Σ and the terminal part Λ. For them we have
derived the equation using variational derivatives, whose
iterations generate the perturbation theory near the atomic limit.
Corrections for the electronic self-energy Σ are calculated
up to the second order with respect to the parameter W/U (W
width of the band), and a mean field type approximation was
formulated, including both charge and spin static fluctuations.
This approximation is actually equivalent to the one used in the
method of Composite Operators, and it describes an insulator-metal
phase transition at half filling reasonably well.
The equations for the Bose-like Green's functions have been
derived, describing the collective modes: the magnons and
doublons. The main term in this equation represents variational
derivatives of the electronic Green's function with respect to the
corresponding fluctuating fields. The properties of the poles of
the doublon Green's functions depend on electronic filling. The
investigation of the special case n=1 demonstrates that the
doublon Green's function has a soft mode at the wave vector
, indicating possible instability of the
uniform paramagnetic phase relatively to the two sublattices
charge ordering. However this instability should compete with an
instability to antiferromagnetic ordering.
The generating functional method with the X operators could be
extended to the other models of strongly correlated systems
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
Rank of divisors on tropical curves
No full textWe investigate, using purely combinatorial methods, structural and algorithmic properties of linear equivalence classes of divisors on tropical curves. In particular, we confirm a conjecture of Baker asserting that the rank of a divisor D on a (non-metric) graph is equal to the rank of D on the corresponding metric graph, and construct an algorithm for computing the rank of a divisor on a tropical curve
COMPACT MODULI OF ENRIQUES SURFACES OF DEGREE 2
No full textWe describe a geometric, stable pair compactification of the moduli space of Enriques surfaces with a numerical polarization of degree 2, and identify it with a semitoroidal compactification of the period space
"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.
Accurately evaluating Young's modulus of polymers through nanoindentations: A phenomenological correction factor to the Oliver and Pharr procedure
No full textThe analysis of nanoindentation force curves collected on polymers through the common Oliver
and Pharr procedure does not lead to a correct evaluation of Young’s modulus. In particular, the estimated elastic
modulus is several times larger than the correct one, thus compromising the possibility of a nanomechanical
characterization of polymers. Pile-up or viscoelasticity is usually blamed for this failure, and a deep analysis of
their influences is attempted in this work. Piling-up can be minimized by indenting on a true nanometer scale,
i.e., at penetration depth smaller than 200 nm. On the other side, it is common knowledge that fast indentations
minimize the effect of viscoelasticity. However, changing the indentation time in a broad range of contact time
(fractions of second up to hundreds of seconds) did not allow the correct estimation of Young’s modulus for the
polymers used in this work. The final result is that the Oliver and Pharr procedure as well as any other procedure
analyzing the unloading curve with elastic contact mechanics models cannot be employed to measure Young’s
modulus of polymers because its application is incorrect from a theoretical point of view, unless the analysis is
limited to the very first nanometers of penetration depth when the contact is perfectly elastic. Viscoelastic contact
mechanics models should instead be employed to characterize these materials
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