Parameterized Complexity of Equitable Coloring

A graph on $n$ vertices is equitably $k$-colorable if it is $k$-colorable and every color is used either $\left\lfloor n/k \right\rfloor$ or $\left\lceil n/k \right\rceil$ times. Such a problem appears to be considerably harder than vertex coloring, being $\mathsf{NP\text{-}Complete}$ even for cographs and interval graphs. In this work, we prove that it is $\mathsf{W[1]\text{-}Hard}$ for block graphs and for disjoint union of split graphs when parameterized by the number of colors; and $\mathsf{W[1]\text{-}Hard}$ for $K_{1,4}$-free interval graphs when parameterized by treewidth, number of colors and maximum degree, generalizing a result by Fellows et al. (2014) through a much simpler reduction. Using a previous result due to Dominique de Werra (1985), we establish a dichotomy for the complexity of equitable coloring of chordal graphs based on the size of the largest induced star. Finally, we show that \textsc{equitable coloring} is $\mathsf{FPT}$ when parameterized by the treewidth of the complement graph

Deciphering M-T diagram of shape memory Heusler alloys: reentrance, plateau and beyond

We present our recent results on temperature behaviour of magnetization observed in Ni_47Mn_39In_14 Heusler alloys. Three regions can be distinguished in the M-T diagram: (I) low temperature martensitic phase (with the Curie temperature T_CM = 140 K), (II) intermediate mixed phase (with the critical temperature T_MS = 230 K) exhibiting a reentrant like behavior (between T_CM and T_MS) and (III) high temperature austenitic phase (with the Curie temperature T_CA = 320 K) exhibiting a rather wide plateau region (between T_MS and T_CA). By arguing that powerful structural transformations, causing drastic modifications of the domain structure in alloys, would also trigger strong fluctuations of the order parameters throughout the entire M-T diagram, we were able to successfully fit all the data by incorporating Gaussian fluctuations (both above and below the above three critical temperatures) into the Ginzburg-Landau scenario

Irreversible magnetization under rotating fields and lock-in effect on ErBa_2Cu_3O_7 single crystal with columnar defects

We have measured the irreversible magnetization M_i of an ErBa_2Cu_3O_7 single crystal with columnar defects (CD), using a technique based on sample rotation under a fixed magnetic field H. This method is valid for samples whose magnetization vector remains perpendicular to the sample surface over a wide angle range - which is the case for platelets and thin films - and presents several advantages over measurements of M_L(H) loops at fixed angles. The resulting M_i(\Theta) curves for several temperatures show a peak in the CD direction at high fields. At lower fields, a very well defined plateau indicative of the vortex lock-in to the CD develops. The H dependence of the lock-in angle \phi_L follows the H^{-1} theoretical prediction, while the temperature dependence is in agreement with entropic smearing effects corresponding to short range vortex-defects interactions.Comment: 7 pages, 6 figures, to be published in Phys. Rev.

Mimosa caesalpiniifolia: estudos de melhoramento genetico realizados pela Embrapa Semi-Arido.

O sabiá ( Mimosa caesalpinifolia Benth. ) ocorre naturalmente em áreas da Caatinga de vários estados da região Nordeste, caracterizando-se por apresentar rápido crescimento, alta capacidade de regeneração e resistência à seca. A espécie é explorada como fonte de madeira , devido à sua alta resistência físico-mecânica , e como alternativa energética pelo seu alto poder calorífico e forragem, pelo seu alto valor nutritivo. Entretanto, a presença de acúleos, caráter dominante na espécie, dificulta o manejo de povoamentos, limitando a sua exploração em condições naturai

Duration of estrus and time of ovulation in superovulated Santa Inês ewes.

Abstract: The aim of this study was to determine the intervals between sponge removal and the onset of estrus, sponge removal and the first detected ovulation, and onset of estrus and the first ovulation, and also to determine the duration of estrus, in superovulated Santa Inês ewes subjected to natural mating (NM) and AI. The trial was done in July and February at Cachoeiras de Macacu?Rio de Janeiro (22°27'S, 43°39'W). Fifteen non-pregnant Santa Inês ewes, age 3.4 ± 1.4 years, weighing 47.8 ± 6.3 kg, with 3.3 ± 0.4 body condition score (scale of 1 to 5), were randomly assigned to 2 groups. Both groups were superovulated using the same protocol and were mated in a crossover design by NM and laparoscopic AI. Estrus was synchronized using intravaginal sponges (60 mg of medroxyprogesterone acetate; Progespon®, Schering Plough Animal Health, São Paulo, Brazil) inserted (Day 0) and maintained for 6 days. On Day 5, the ewes received IM injections of 300 IU of eCG (Novormon®, Schering Plough Animal Health) and 0.0375 mg of cloprostenol (Prolise®, Tecnopec, São Paulo, Brazil). Twelve hours after sponge removal, 0.025 mg of gonadorelin acetate (Gestran®, Tecnopec) was administered IM. Superovulation started 60 h after sponge removal and consisted of 5 IU kg -1 of porcine FSH (pFSH; Pluset®, Hertape Calier, Minas Gerais, Brazil) IM in 6 decreasing doses (25, 25, 15, 15, 10, and 10%) at 12-h intervals. At the first pFSH dose, new sponges were inserted. At the fifth pFSH dose, 0.0375 mg of cloprostenol was administered IM and the sponges were removed. After the sponge removal, the NM group was exposed to rams twice per day for mating, until the end of estrus. In the AI group, estrus was detected using a teaser with the penis diverted. The females were permitted to be mounted twice per day until the end of estrus, and were inseminated with frozen-thawed semen 24 and 36 h after the end of superovulation. The follicular development and ovulation time were observed using real-time ultrasonography (8.0 MHz Pie Medical®, Aquila Vet, Tokyo, Japan) at 12-h intervals. For statistical analysis, a Student's t-test was performed (5% significance level) using the BioEstat program. Results are presented as mean ± standard deviation. The time from sponge removal to onset of estrus and the duration of estrus did not differ between NM and AI groups (31.79 ± 5.94 v. 25.25 ± 10.38 h and 29.89 ± 11.54 v. 26.66 ± 8.67 h, respectively). The time from sponge removal to ovulation and from onset of estrus to the first ovulation were shorter (P < 0.001) in the NM group (32.11 ± 12.72 v. 56.48 ± 15.39 h and 8.61 ± 5.99 v. 32.25 ± 18.57 h, respectively). The time from sponge removal to ovulation in July and February was 56.07 ± 7.27 versus 56.83 ± 20.72 in the AI group and 29.54 ± 0.56 versus 33.83 ± 19.02 in the NM group, respectively, suggesting that the season of the year in a tropical region did not influence the ovulation time for each treatment. Possibly, the mechanical stimulation induced by the contact of the penis with the vagina fornix and by the accessory sex glands fluids in mating hastened the ovulation time in the NM group. The service can shorten the time of ovulation

An interacting model for the cosmological dark sector

We discuss a new interacting model for the cosmological dark sector in which the attenuated dilution of cold dark matter scales as $a^{-3}f(a)$, where f(a) is an arbitrary function of the cosmic scale factor $a$. From thermodynamic arguments, we show that f(a) is proportional to entropy source of the particle creation process. In order to investigate the cosmological consequences of this kind of interacting models, we expand f(a) in a power series and viable cosmological solutions are obtained. Finally, we use current observational data to place constraints on the interacting function f(a).Comment: 5 pages, 3 figures, Phys. Rev. D (in press