213 research outputs found
Psi-floor diagrams and a Caporaso-Harris type recursion
Floor diagrams are combinatorial objects which organize the count of tropical
plane curves satisfying point conditions. In this paper we introduce Psi-floor
diagrams which count tropical curves satisfying not only point conditions but
also conditions given by Psi-classes (together with points). We then generalize
our definition to relative Psi-floor diagrams and prove a Caporaso-Harris type
formula for the corresponding numbers. This formula is shown to coincide with
the classical Caporaso-Harris formula for relative plane descendant
Gromov-Witten invariants. As a consequence, we can conclude that in our case
relative descendant Gromov-Witten invariants equal their tropical counterparts.Comment: minor changes to match the published versio
Enumerative aspects of the Gross-Siebert program
We present enumerative aspects of the Gross-Siebert program in this
introductory survey. After sketching the program's main themes and goals, we
review the basic definitions and results of logarithmic and tropical geometry.
We give examples and a proof for counting algebraic curves via tropical curves.
To illustrate an application of tropical geometry and the Gross-Siebert program
to mirror symmetry, we discuss the mirror symmetry of the projective plane.Comment: A version of these notes will appear as a chapter in an upcoming
Fields Institute volume. 81 page
Annual post-market environmental monitoring (PMEM) report on the cultivation of genetically modified maize MON 810 in 2014 from Monsanto Europe S.A.
Following a request from the European Commission, the Panel on Genetically Modified Organisms of the European Food Safety Authority (GMO Panel) assessed the annual post-market environmental monitoring (PMEM) report for the 2014 growing season of maize MON 810 provided by Monsanto Europe S.A. The GMO Panel concludes that the insect resistance monitoring data do not indicate a decrease in susceptibility of field Iberian populations of corn borers to the Cry1Ab protein over the 2014 season. However, as the methodology for insect resistance monitoring remained unchanged compared to previous PMEM reports, the GMO Panel reiterates its previous recommendations for improvement of the insect resistance management plan. The GMO Panel considers that the farmer alert system to report complaints regarding product performance could complement the information obtained from the laboratory bioassays, but encourages the consent holder to provide more information in order to be in a position to appraise its usefulness. The data on general surveillance activities do not indicate any unanticipated adverse effects on human and animal health or the environment arising from the cultivation of maize MON 810 cultivation in 2014. The GMO Panel reiterates its previous recommendations to improve the methodology for the analysis of farmer questionnaires and conduct of the literature review in future annual PMEM reports on maize MON 810. The GMO Panel urges the consent holder to consider how to make best use of the information recorded in national registers to optimise sampling for farmer questionnaires, and requests to continue reviewing and discussing relevant scientific publications on possible adverse effects of maize MON 810 on rove beetles. Also, the GMO Panel encourages relevant parties to continue developing a
methodological framework to use existing networks in the broader context of environmental monitorin
Birational cobordism invariance of uniruled symplectic manifolds
A symplectic manifold is called {\em (symplectically) uniruled}
if there is a nonzero genus zero GW invariant involving a point constraint. We
prove that symplectic uniruledness is invariant under symplectic blow-up and
blow-down. This theorem follows from a general Relative/Absolute correspondence
for a symplectic manifold together with a symplectic submanifold. A direct
consequence is that symplectic uniruledness is a symplectic birational
invariant. Here we use Guillemin and Sternberg's notion of cobordism as the
symplectic analogue of the birational equivalence.Comment: To appear in Invent. Mat
The European internet-based patient and research database for primary immunodeficiencies: results 2006-2008
Primary immunodeficiencies (PID) are rare diseases; therefore transnational studies are essential to maximize the scientific outcome and to improve diagnosis and therapy. In order to estimate the prevalence of PID in Europe as well as to establish and evaluate harmonized guidelines for the diagnosis and treatment of PID, the European Society for Immunodeficiencies (ESID) has developed an internet-based database for clinical and research data on patients with PID. This database is a platform for epidemiological analyses as well as the development of new diagnostic and therapeutic strategies and the identification of novel disease-associated genes. Within 4 years, 7430 patients from 39 countries have been documented in the ESID database. Common variable immunodeficiency (CVID) represents the most common entity, with 1540 patients or 20.7% of all entries, followed by isolated immunoglobulin (Ig)G subclass deficiency (546 patients, 7.4%). Evaluations show that the average life expectancy for PID patients varies from 1 to 49 years (median), depending on the type of PID. The prevalence and incidence of PID remains a key question to be answered. As the registration progress is far from finished we can only calculate minimum values for PID, with e.g. France currently showing a minimum prevalence of 3.72 patients per 100,000 inhabitants. The most frequently documented permanent treatment is immunoglobulin replacement; 2819 patients (42% of all patients alive) currently receive this form of treatment
Changing Bee and Hoverfly Pollinator Assemblages along an Urban-Rural Gradient
The potential for reduced pollination ecosystem service due to global declines of bees and other pollinators is cause for considerable concern. Habitat degradation, destruction and fragmentation due to agricultural intensification have historically been the main causes of this pollinator decline. However, despite increasing and accelerating levels of global urbanization, very little research has investigated the effects of urbanization on pollinator assemblages. We assessed changes in the diversity, abundance and species composition of bee and hoverfly pollinator assemblages in urban, suburban, and rural sites across a UK city.Bees and hoverflies were trapped and netted at 24 sites of similar habitat character (churchyards and cemeteries) that varied in position along a gradient of urbanization. Local habitat quality (altitude, shelter from wind, diversity and abundance of flowers), and the broader-scale degree of urbanization (e.g. percentage of built landscape and gardens within 100 m, 250 m, 500 m, 1 km, and 2.5 km of the site) were assessed for each study site. The diversity and abundance of pollinators were both significantly negatively associated with higher levels of urbanization. Assemblage composition changed along the urbanization gradient with some species positively associated with urban and suburban land-use, but more species negatively so. Pollinator assemblages were positively affected by good site habitat quality, in particular the availability of flowering plants.Our results show that urban areas can support diverse pollinator assemblages, but that this capacity is strongly affected by local habitat quality. Nonetheless, in both urban and suburban areas of the city the assemblages had fewer individuals and lower diversity than similar rural habitats. The unique development histories of different urban areas, and the difficulty of assessing mobile pollinator assemblages in just part of their range, mean that complementary studies in different cities and urban habitats are required to discover if these findings are more widely applicable
The Occupations and Human Capital of U.S. Immigrants
This paper estimates the multi-dimensional human capital endowments of immigrants by characterizing their occupational decisions. This approach allows for estimation of physical skill and cognitive ability endowments, which are difficult to measure directly. Estimation implies that immigrants as a whole are abundant in cognitive ability and scarce in experience/training and communication skills. Counterfactual estimates of the wage impacts of immigration are skewed: the largest gain from preventing immigration is 3.2% higher wages, but the largest loss is 0.3% lower
wages. Crowding of immigrants into select occupations plays a minor role in explaining these impacts; occupations’ skill attributes explain the bulk
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