1,721,076 research outputs found
Recursive Betti numbers for Cohen-Macaulay d-partite clutters arising from posets
No full textA natural extension of bipartite graphs are d-partite clutters, where d >= 2 is an integer. For a poset P, Ene, Herzog and Mohammadi introduced the d-partite clutter C_{P,d} of multichains of length d in P, showing that it is Cohen-Macaulay. We prove that the cover ideal of C_{P,d} admits an x(i)-splitting, determining a recursive formula for its Betti numbers and generalizing a result of Francisco, Ha and Van Tuyl on the cover ideal of Cohen-Macaulay bipartite graphs. Moreover we prove a Betti splitting result for the Alexander dual of a Cohen Macaulay simplicial complex. Interesting examples are given, in particular the first example of ideal that does not admit Betti splitting in any characteristic
Binomial edge ideals of bipartite graphs
No full textBinomial edge ideals are a noteworthy class of binomial ideals that can be associated with graphs, generalizing the ideals of 2-minors. For bipartite graphs we prove the converse of Hartshorne’s Connectedness Theorem, according to which if an ideal is Cohen–Macaulay, then its dual graph is connected. This allows us to classify Cohen–Macaulay binomial edge ideals of bipartite graphs, giving an explicit and recursive construction in graph-theoretical terms. This result represents a binomial analogue of the celebrated characterization of (monomial) edge ideals of bipartite graphs due to Herzog
and Hibi (2005)
Indagine preliminare sulla possibilità di introdurre nuove classi di valutazione del fattore “taglia” per bovine di razza Pezzata Rossa Italiana
No full textEmbryo production and quality in dairy cattle is enhanced by manual transrectal ablation of the dominant follicle prior to superovulation
Full text linkThe objective was to determine effects of manual transrectal ablation of the largest (dominant) ovarian follicle on days 7 or 8 of the cycle (estrus = day 0) to synchronize wave emergence before superovulation. Superovulation was performed in 167 donors, 32 nulliparous, 36 primiparous and 99 multiparous Holsteins. They were randomly allocated into 3 groups: control group (n=64, including 15 cows where the follicle failed to rupture by light digital pressure), dominant follicle ablation on day 7 (n=57) and dominant follicle ablation on day 8 (n=46). Superstimulatory treatments started on day 10 for control or 1 day after ablation. Superovulation was induced by 9 im injections of decreasing dosage of gonadotrophins at 12-hour intervals over 4.5 days. PGF2α was administered in 2 im injections at the time of the seventh and the eighth injections of gonadotrophins. All females were artificially inseminated with frozen-thawed semen. Seven days after estrus embryos/ova were recovered by flushing the uterine horns, classified for stage and quality according to the IETS guidelines, and transferred fresh or frozen. Treated cows were subsequently monitored for adverse effects that could affect reproductive parameters or reproductive culling rate at 270 days post-partum. Total numbers of recovered structures and transferable embryos were lower (P<0.05) in control (7.8 ± 4.5 and 5.1 ± 3.3, respectively; mean ± SD) compared to ablation 7 (9.0 ± 2.5 and 7.0 ± 1.9) and ablation 8 (9.6 ± 3.4 and 6.9 ± 2.5) groups. There was no difference (P>0.05) among groups in mean grade of transferable embryos, but percentage of Grade-I embryos were higher in ablation 8 group (47.3%) than in control (37.9%), whereas Grade-II embryos were lower in ablation 8 group (37.5%) compared to control (45.6%) (P<0.05). Percentage of unfertilized oocytes was higher (P<0.05) in control (14.4%) than in ablation 8 group (9.8%), whereas degenerating embryos were lower (P<0.05) in ablation 7 group (12.2%) than in control (20.0%). Conversely, percentage of morulae was higher (P<0.05) in ablation 7 group (32.8%) than control (25.5%). Reproductive parameters and culling rates were similar among groups (P>0.05). In conclusion, improvements in embryo number and quality were achieved by manually ablating the dominant ovarian follicle on days 7 or 8. Furthermore, there was no evidence that judicious manual ablation could have any detrimental effect on subsequent reproductive performance and culling rate
Cohen-Macaulay binomial edge ideals of small graphs
No full textA combinatorial property that characterizes Cohen-Macaulay binomial edge ideals has long been elusive. A recent conjecture ties the Cohen-Macaulayness of a binomial edge ideal J_G to special disconnecting sets of vertices of its underlying graph G, called cut sets. More precisely, the conjecture states that J_G is Cohen-Macaulay if and only if J_G is unmixed and the collection of the cut sets of G is an accessible set system. In this paper we prove the conjecture theoretically for all graphs with up to 12 vertices and develop an algorithm that allows to computationally check the conjecture for all graphs with up to 15 vertices and all blocks with whiskers where the block has at most 11 vertices. This significantly extends previous computational results
Embryo transfer for dissemination of κ-casein bb genotype and improvement of milk clotting properties
Full text linkBackground and Objective: Milk production and cheese industries need to balance the genetic progress in milk yield and protein content with the need for improving milk coagulation properties and workability. Our objective was to determine how rapidly and to what extent Milk Clotting Properties (MCP) could be improved by using Embryo Transfer (ET) to increase the frequency of the κ-casein BB genotype and reducing A and E variants in an Italian Holstein herd with a low prevalence of the favorable genotype. Materials and Methods: In a herd of 352 cows, with a relatively low distribution of the favorable κ-casein BB genotype (11.0%) and poor milk clotting properties, κ-casein BB animals were superovulated (36 out of 39) and bred with SexedULTRATM sex-sorted semen of κ-casein BB bulls in order to improve milk workability and cheese yield. Forty-five embryo transfer sessions yielded 203 embryos, 108 pregnancies and 98 females, of which 89 calved and entered the first lactation. Results: Milk composition and coagulation properties differed significantly among the groups considered (p<0.05) and were more favourable for cheese-making in the groups with a higher percentage of κ-casein BB animals whose tank and pool milk samples consistently showed greater (p<0.05) fat, protein, casein and κ-casein B content and improved clotting properties with lower (p<0.05) r and k20 and higher (p<0.05) a30. Conclusion: In the relatively short period of the project, the embryo transfer program allowed the establishment of a herd whose milk has considerably improved composition and clotting properties
P-flag spaces and incidence stratifications
Full text linkFor any finite poset P, we introduce a homogeneous space as a quotient of the general linear group. When P is a chain this quotient is a complete flag variety. Moreover, we provide partitions for any set in a projective space, induced by the action of incidence groups of posets. Our general framework allows to deal with several combinatorial and geometric objects, unifying and extending different structures such as Bruhat orders, parking functions and weak orders on matroids. We introduce the notion of P-flag matroid, extending flag matroids
Superovulation protocols for dairy cows bred with SexedULTRATM sex-sorted semen
Full text linkContents The objective was to compare embryo yield and quality in lactating dairy cows superovulated (SO) with varying amounts of gonadotropins and FSH:LH ratios and inseminated with SexedULTRA (TM) sex-sorted semen. The SO treatments (n = 77) involved 3 protocols: groups F700 and F1000 were given total doses of 700 and 1,000 IU of Folltropin (FSH:LH ratio 49:1), respectively, whereas group F700P300 was given 700 IU of Folltropin + 300 IU of Pluset (FSH:LH ratio 1:1). Cows were artificially inseminated 3 times over a 10-hr interval with frozen-thawed SexedULTRA (TM) sex-sorted semen (total of 10 x 10(6) sex-sorted sperm), starting 18 hr after onset of oestrus, with embryos/ova recovered 7 d after oestrus. Total number of recovered structures and transferable embryos were lower (p < 0.05) in F700 (4.7 +/- 3.0 and 1.9 +/- 1.7, respectively; mean +/- SD) compared to F1000 (8.1 +/- 3.8 and 4.4 +/- 2.6) and F700P300 (8.5 +/- 6.4 and 4.5 +/- 3.3). Percentage of cows ovulating >50% of follicles >= 0.8 cm in diameter was lower (p < 0.05) in F700 (35.5%) than in F1000 (82.4%) and F700P300 (73.1%). Percentage of unfertilized oocytes was higher (p < 0.05) in F700 (45.0% vs. 27.7% for F1000 and 29.0% for F700P300) whereas percentage of morulae was higher (p < 0.05) in F1000 (19.3% vs. 8.7% for F700 and 12.2% for F700P300). Embryo quality was similar among groups (p > 0.05). In conclusion, embryo production in lactating dairy cows was improved by increasing total dose of gonadotropins from 700 to 1,000 IU, with SexedULTRA (TM) sex-sorted semen yielding satisfactory fertilization rates and embryo quality
- …
