1,999 research outputs found
Incidence of splayleg pigs in Nebraska litter size selection lines
Genetic parameters for the splayleg (SL) condition were estimated from 37,673 records of pigs from six lines derived from a Large White–Landrace base population. Random selection for 22 generations was practiced in Lines C1 and C2. Line C2 was derived from C1 at Generation 8. Selection lines were as follows: 1) Line I, selected 11 generations for an index of ovulation rate and embryonic survival followed by 11 generations of selection for litter size; 2) Line IOL, derived from Line I at Generation 8 and which underwent eight generations of two-stage selection for ovulation rate and number of fully formed pigs per litter followed by four generations of litter size selection; 3) Line COL, derived from Line C1 at Generation 8 and selected eight generations in two stages for ovulation rate and number of fully formed pigs followed by four generations of litter size selection; and 4) Line T, selected 12 generations for increased testis size. From logistic models, it was found that boars were 224% more likely to have SL than gilts (P \u3c 0.01). Decreases in birth weight, dam age at puberty, dam nipple number, and dam embryonic survival, and increases in dam litter size and inbreeding increased the odds of SL (P \u3c 0.05). Direct and maternal heritabilities of SL were 0.07 and 0.16, respectively, and the correlation between direct and maternal effects was −0.24. Correlations between direct genetic effects for SL and number born alive, nipple number, birth weight, age at puberty, and embryonic survival were −0.19, −0.36, 0.23, −0.19, and −0.32, respectively. Except for the correlation of 0.32 between maternal effects for SL and direct effects for number of live pigs, correlations of SL maternal genetic effects with direct genetic effects of other traits were less than 0.11. Annual direct genetic trends (%) for SL in I, IOL, COL, T, C1, and C2 were −0.003 ± 0.003, 0.121 ± 0.012, −0.273 ± 0.009, 0.243 ± 0.014, −0.274 ± 0.004, and 0.086 ± 0.008, respectively; annual maternal genetic trends (%) were 0.106 ± 0.004, 0.508 ± 0.019, 0.383 ± 0.015, 0.527 ± 0.024, 0.188 ± 0.005, and 0.113 ± 0.012, respectively. Annual genetic maternal trend in Line I after Generation 12 was 0.339 ± 0.014. Maternal breeding value for SL is expected to increase as a correlated response to selection for increased litter size and increased size of testes
Digital Preservation and Web Access to the Konkoly Observatory Schmidt Telescope Plate Archive
ACM Computing Classification System (1998): J.2.The digital preservation of the Konkoly Observatory Schmidt
telescope plates, as well as the web access to the plate previews, aim for
the preservation of this scientific heritage and the re-use of the astronomical
photographic plates in time domain astronomy. The photographic plates
used as detectors and information storage at astronomical observations with
the Konkoly Schmidt telescope had been obtained in the period 1962–1996.
The work on the digital plate preservation and web access started in 2001
with creation of an electronic plate catalogue and the digitization of selected
representative plates as well as with interlinking of the publishing in Konkoly
Observatory Information Bulletin on Variable Stars (IBVS) with the Wide-Field Plate Database (WFPDB) developing in Sofia. We describe the process
of the digitization of the Konkoly Schmidt telescope plates.This work is supported by the bilateral project between the Bulgarian Academy of Sciences
and the Hungarian Academy of Sciences and partially by the grants BG NSF DO-02-273 and
BG NSF DO-02-275
Electron interferometry with nano-gratings
We present an electron interferometer based on near-field diffraction from
two nanostructure gratings. Lau fringes are observed with an imaging detector,
and revivals in the fringe visibility occur as the separation between gratings
is increased from 0 to 3 mm. This verifies that electron beams diffracted by
nanostructures remain coherent after propagating farther than the Talbot length
= 1.2 mm, and hence is a proof of principle for the
function of a Talbot-Lau interferometer for electrons. Distorted fringes due to
a phase object demonstrates an application for this new type of electron
interferometer.Comment: 4 pgs, 6 figure
Effects of habitat, cattle grazing and selective logging on seedling survival and growth in dry forests of Central Brazil.
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Previous issue date: 2008-02-2
The Role of Plexin-D1 in the Adaptive Immune System: Implications for Humoral Immunity
Plexin and semaphorin molecules direct axon localization by generating attractive and repulsive forces. Recently, plexin and semaphorin molecules have been shown to control cell movement and cell-cell interaction in the immune system. In this study, we characterize the expression and function of plexin-D1 in the immune system. We show that plexin-D1 is highly expressed in thymocyte, B cell and dendritic cell compartments. Absence of Plexin-D1 resulted in aberrant thymic development and impaired DP thymocyte migration from the cortex to the medulla. However, we found that absence of plexin-D1 did not affect the formation of mature T cell compartments and peripheral T cells were capable to respond to antigenic challenge. Normal B cell development and maturation was observed in PlxnD1-/- mice; however, these mice exhibited defective germinal center (GC) reactions during T-dependent immune activation. Protective humoral immune responses depend upon the generation of memory B cells and long-lived plasma cells formed in the GC reaction. We demonstrate that Plexin-D1 is responsible for migration of activated B cells into the GC. We correlate these observations with reduced migration of PlxnD1-/- B cells towards the GC chemokines, CXCL12, CXCL13 and CCL19. Accordingly, PlxnD1-/- mice exhibited defective production of IgG1 and IgG2b, but not IgG3 serum antibody, accompanied by reductions in high-affinity antibody, long-lived bone marrow plasmacytes, and recall humoral memory response. These data show a new role for plexin molecules in the GC reaction and generation of immunologic memory
The Midpoint Rule as a Variational--Symplectic Integrator. I. Hamiltonian Systems
Numerical algorithms based on variational and symplectic integrators exhibit
special features that make them promising candidates for application to general
relativity and other constrained Hamiltonian systems. This paper lays part of
the foundation for such applications. The midpoint rule for Hamilton's
equations is examined from the perspectives of variational and symplectic
integrators. It is shown that the midpoint rule preserves the symplectic form,
conserves Noether charges, and exhibits excellent long--term energy behavior.
The energy behavior is explained by the result, shown here, that the midpoint
rule exactly conserves a phase space function that is close to the Hamiltonian.
The presentation includes several examples.Comment: 11 pages, 8 figures, REVTe
Coverage, efficacy or dosing interval: which factor predominantly influences the impact of routine childhood vaccination for the prevention of varicella? A model-based study for Italy
Background: Varicella is a highly infectious disease with a significant public health and economic burden, which can be prevented with childhood routine varicella vaccination. Vaccination strategies differ by country. Some factors are known to play an important role (number of doses, coverage, dosing interval, efficacy and catch-up programmes), however, their relative impact on the reduction of varicella in the population remains unclear. This paper aims to help policy makers prioritise the critical factors to achieve the most successful vaccination programme with the available budget. Methods: Scenarios assessed the impact of different vaccination strategies on reduction of varicella disease in the population. A dynamic transmission model was used and adapted to fit Italian demographics and population mixing patterns. Inputs included coverage, number of doses, dosing intervals, first-dose efficacy and availability of catch-up programmes, based on strategies currently used or likely to be used in different countries. The time horizon was 30 years. Results: Both one- and two-dose routine varicella vaccination strategies prevented a comparable number of varicella cases with complications, but two-doses provided broader protection due to prevention of a higher number of milder varicella cases. A catch-up programme in susceptible adolescents aged 10-14 years old reduced varicella cases by 27-43 % in older children, which are often more severe than in younger children. Coverage, for all strategies, sustained at high levels achieved the largest reduction in varicella. In general, a 20 % increase in coverage resulted in a further 27-31 % reduction in varicella cases. When high coverage is reached, the impact of dosing interval and first-dose vaccine efficacy had a relatively lower impact on disease prevention in the population. Compared to the long (11 years) dosing interval, the short (5 months) and medium (5 years) interval schedules reduced varicella cases by a further 5-13 % and 2-5 %, respectively. Similarly, a 10 % increase in first-dose efficacy (from 65 to 75 % efficacy) prevented 2-5 % more varicella cases, suggesting it is the least influential factor when considering routine varicella vaccination. Conclusions: Vaccination strategies can be implemented differently in each country depending on their needs, infrastructure and healthcare budget. However, ensuring high coverage remains the critical success factor for significant prevention of varicella when introducing varicella vaccination in the national immunisation programme
Construction of two whole genome radiation hybrid panels for dromedary (Camelus dromedarius): 5000RAD and 15000RAD
The availability of genomic resources including linkage information for camelids has been very limited. Here, we describe the construction of a set of two radiation hybrid (RH) panels (5000RAD and 15000RAD) for the dromedary (Camelus dromedarius) as a permanent genetic resource for camel genome researchers worldwide. For the 5000RAD panel, a total of 245 female camel-hamster radiation hybrid clones were collected, of which 186 were screened with 44 custom designed marker loci distributed throughout camel genome. The overall mean retention frequency (RF) of the final set of 93 hybrids was 47.7%. For the 15000RAD panel, 238 male dromedary-hamster radiation hybrid clones were collected, of which 93 were tested using 44 PCR markers. The final set of 90 clones had a mean RF of 39.9%. This 15000RAD panel is an important high-resolution complement to the main 5000RAD panel and an indispensable tool for resolving complex genomic regions. This valuable genetic resource of dromedary RH panels is expected to be instrumental for constructing a high resolution camel genome map. Construction of the set of RH panels is essential step toward chromosome level reference quality genome assembly that is critical for advancing camelid genomics and the development of custom genomic tools
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