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Search Results: 1 - 10 of 53 matches for " rhim "
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Effects of group size on agonistic behaviors of commercially housed growing pigs Efecto del tama o del grupo sobre la conducta agonística de cerdos en crecimiento alojados en instalaciones comerciales Efeitos do tamanho do grupo sobre a conduta agonística de suínos em crescimento alojados em instala es comerciais
Shin-Jae Rhim
Revista Colombiana de Ciencias Pecuarias , 2012,
Abstract: Objective: this study was conducted to understand the effects of group size on the agonistic behaviors of pigs reared at differing pen densities. Methods: thirty groups of pigs (a total of 350 individuals) housed at low, medium, and high group density (5, 10, or 20 individuals in 6.0 m x 6.0 m pens) were consecutively observed for 10 h on days 30, 90, and 180 with the aid of video technology. Results: the frequency of vocalizations was lower at low group density and higher at high group density on all investigated days. Pigs housed at high group density showed significantly more agonistic behaviors than those at low group density. Conclusions: the study reveals a higher level of aggression in older pigs and at high group density. It is concluded that group density is a major cause of the observed agonistic behaviors. Objetivo: este estudio busca comprender los efectos del tama o del grupo sobre los comportamientos agonísticos de cerdos criados en corrales bajo diferentes densidades de animales por unidad de espacio. Métodos: treinta grupos de cerdos (un total de 350 animales) alojados en baja, media y alta densidad de animales (5, 10 ó 20 animales en corrales de 6.0 x 6.0 m) fueron observados durante 10 horas consecutivas en los días 30, 90, y 180 con la ayuda de tecnología de vídeo. Resultados: la frecuencia de vocalizaciones fue menor en el grupo de baja densidad de animales, y mayor en el grupo de alta densidad durante todos los días estudiados. Los cerdos alojados en grupos con alta densidad animal mostraron un comportamiento significativamente más agonístico que aquellos en baja densidad. Conclusiones: este estudio revela que existe un mayor nivel de agresión en los cerdos más viejos y en grupos con mayor densidad de animales. Se concluye que la densidad de alojamiento es una causa importante de la conducta agonística observada. Objetivo: este estudo busca compreender os efeitos do tamanho do grupo acerca dos comportamentos agonísticos dos suínos criados em corrais sobre diferentes densidades de animais por unidade de espa o. Métodos: trinta grupos de suínos (um total de 350 animais) alojados em baixa, meia e alta densidade de animais (5, 10 ou 20 animais em corrais de 6.0 x 6.0 m) foram observados durante 10 horas consecutivas nos dias 30, 90 e 180 com a ajuda de tecnologia de vídeo. Resultados: a frequência de vocaliza es foi menor no grupo de baixa densidade de animais, e maior no grupo de alta densidade durante todos os dias estudados. Os suínos alojados em grupos com alta densidade animal mostraram um comportamento significativamente mais ago
Vocalization and behavior of Holstein cows and calves after partial and complete separation Vocalización y comportamiento de vacas y terneros Holstein luego de separación parcial y total Vocaliza o e comportamento de bezerros e vacas Holandesas após separa o parcial e completa
Rhim Shin-Jae
Revista Colombiana de Ciencias Pecuarias , 2013,
Abstract: Background: a potential negative impact on the welfare and growth of the calf occurs when it is separated from its mother. Objective: this study was conducted in order to understand how the vocal and behavioral characteristics of cows and calves differ between partial and complete separations. Methods: 30 cows and their calves (60 study participants in total) housed in different barns were observed for 10 consecutive hours using video technology on days 1, 6, and 11 after partial and complete separations. Results: vocalization frequency was higher (p<0.05) following partial separation for both cows and calves. After complete separation, cows exhibited significantly more (p<0.05) lying behavior as well as fewer (p<0.05) standing and sniffing behaviors. Conclusions: the study revealed higher intensity and occurrence of vocalization levels and behavioral changes in cows and calves following partial separation. It is concluded that partial separation could imply higher interaction between cows and calves and also greater animal welfare challenges in comparison with complete separation. Antecedentes: un posible impacto negativo sobre el bienestar y el crecimiento del ternero se produce cuando este se separa de su madre. Objetivo: este estudio tuvo como objetivo comprender como las características vocales y de comportamiento de vacas y terneros difieren luego de la separación parcial o completa entre ambos. Métodos: 30 vacas y sus terneros (60 animales en total) alojados en establos separados fueron observados durante 10 horas consecutivas utilizando tecnología de vídeo durante los días 1, 6, y 11 después de separacion parcial o completa. Resultados: la frecuencia de vocalización fue mayor (p <0,05) tras la separación parcial de vacas y ternero. Después de la separación completa, las vacas yacían más en el piso (p <0,05), permanecían menos tiempo de pie y tenían menos comportamiento de olfateo (p <0,05). Conclusiones: el estudio reveló una mayor intensidad y frecuencia de vocalizaciones y cambios de comportamiento en las vacas y los terneros tras la separación parcial. Se concluye que la separación parcial podría implicar una mayor interacción entre las vacas y los terneros y también mayores desafíos de bienestar animal en comparación con la separación completa. Antecedentes: um possível impacto negativo no bem-estar e crescimento ocorre quando o bezerro é separado de sua m e. Objetivo: descrever as características comportamentais e emiss es vocais de bezerros e vacas Holandesas após separa o parcial e completa. Métodos: 30 vacas e seus bezerros (para um tot
Allelopathic interaction of pepper (Capsicum annuum) and pearl millet (Pennisetum glaucum) intercropped
Leila Radouane,Thouraya Rhim
International Journal of Environment , 2014, DOI: 10.3126/ije.v3i1.9940
Abstract: Intercropping is common practice in many regions of Tunisia, particularly in Cap-Bon where different crops such as tomato, pepper, cucumber, peanut, corn, pearl millet and sorghum are grown together in the same field and at the same time for self-sufficiency. A number of these crops and vegetables are known for their allelopathic activities. The interaction between plants could be within the individuals of the same species (intraspecific interaction or autotoxicity) or between different species (interspecific interaction or teletotoxicity). Little is known about allelopathic interaction of some of these intercropped plants in mixed farming systems in our local conditions. Therefore, the objectives of the present investigation are to evaluate, under laboratory condition, the allelopathic effect of mixed crops, which interacted positively or negatively when cultivated together in the same field. Two plant species were used to study the effects of their aqueous extract on germination and growth of each other (pepper and pearl millet). The results suggested that aqueous extracts from shoots and roots significantly inhibited germination and seedling growth and the inhibitory effects were increased proportionally with the extract concentration. The shoot and root aqueous extract also exhibited intraspecific and interspecific allelopathy. Generally, it was observed that roots were more toxic than shoots. For root extract, the highest inhibition percentage was gained from the effect of pearl millet on pepper (40%) and highest autotoxicity was observed from pearl millet (36%). The effect of shoot extract on germination indicated that the highest reduction (55%) was obtained from pepper shoot extract on pearl millet and highest autotoxicity was observed from pepper which reached (45%). In most cases autotoxicity appeared to be more severe than teletotoxicity, on seed germination of the two intercropped plant species. DOI: http://dx.doi.org/10.3126/ije.v3i1.9940 International Journal of Environment Vol.3(1) 2014: 32-40
Current Possible Drug Therapies for Ovarian Cancer  [PDF]
Jungyeob Seoung, Young-Han Park, Chaechun Rhim, Sungju Kim
Journal of Cancer Therapy (JCT) , 2014, DOI: 10.4236/jct.2014.513122
Abstract:

Ovarian cancer is the most aggressive gynecologic cancer of the heterogenous phenotypes. Development of the new chemotherapeutic agents and drug delivery mode makes better outcomes for patient treatments. Optimal cytoreductive therapy followed by molecular targeting therapy, intraperitoneal chemotherapy and dose dense chemotherapy is a hot therapeutic concept in ovarian cancers. In our review, we will introduce recent therapeutic advances in epithelial ovarian cancer patients.

Edge states of zigzag bilayer graphite nanoribbons
Jun-Won Rhim,Kyungsun Moon
Physics , 2008, DOI: 10.1088/0953-8984/20/36/365202
Abstract: Electronic structures of the zigzag bilayer graphite nanoribbons(Z-BGNR) with various ribbon width $N$ are studied within the tight binding approximation. Neglecting the inter-layer hopping amplitude $\gamma_4$, which is an order of magnitude smaller than the other inter-layer hopping parameters $\gamma_1$ and $\gamma_3$, there exist two fixed Fermi points $\pm k^*$ independent of the ribbon width with the peculiar energy dispersion near $k^*$ as $\ve (k) \sim \pm (k-k^*)^N$. By investigating the edge states of the Z-BGNR, we notice that the trigonal warping of the bilayer graphene sheets are reflected on in the edge state structure. With the inclusion of $\gamma_4$, the above two Fermi points are not fixed, but drift toward the vicinity of the Dirac point with the increase of the width $N$ as shown by the finite scaling method and the peculiar dispersions change to the parabolic ones. The edge magnetism of the Z-BGNR is also examined by solving the half-filled Hubbard Hamiltonian for the ribbon using the Hartree-Fock approximation. We have shown that within the same side of the edges, the edge spins are aligned ferromagnetically for the experimentally relevant set of parameters.
Landau Level Quantization and Almost Flat Modes in Three-dimensional Semi-metals with Nodal Ring Spectra
Jun-Won Rhim,Yong Baek Kim
Physics , 2015, DOI: 10.1103/PhysRevB.92.045126
Abstract: We investigate novel Landau level structures of semi-metals with nodal ring dispersions. When the magnetic field is applied parallel to the plane in which the ring lies, there exist almost non-dispersive Landau levels at the Fermi level (E_F = 0) as a function of the momentum along the field direction inside the ring. We show that the Landau levels at each momentum along the field direction can be described by the Hamiltonian for the graphene bilayer with fictitious inter-layer couplings under a tilted magnetic field. Near the center of the ring where the inter-layer coupling is negligible, we have Dirac Landau levels which explain the appearance of the zero modes. Although the inter-layer hopping amplitudes become finite at higher momenta, the splitting of zero modes is exponentially small and they remain almost flat due to the finite artificial in-plane component of the magnetic field. The emergence of the density of states peak at the Fermi level would be a hallmark of the ring dispersion.
Quantum Spin Hall Effect in Graphene Nanoribbons: Effect of Edge Geometry
Jun-Won Rhim,Kyungsun Moon
Physics , 2011, DOI: 10.1103/PhysRevB.84.035402
Abstract: There has been tremendous recent progress in realizing topological insulator initiated by the proposal of Kane and Mele for the graphene system. They have suggested that the odd $Z_2$ index for the graphene manifests the spin filtered edge states for the graphene nanoribbons, which lead to the quantum spin Hall effect(QSHE). Here we investigate the role of the spin-orbit interaction both for the zigzag and armchair nanoribbons with special care in the edge geometry. For the pristine zigzag nanoribbons, we have shown that one of the $\sigma$ edge bands located near E=0 lifts up the energy of the spin filtered chiral edge states at the zone boundary by warping the $\pi$-edge bands, and hence the QSHE does not occur. Upon increasing the carrier density above a certain critical value, the spin filtered edge states are formed leading to the QSHE. We suggest that the hydrogen passivation on the edge can recover the original feature of the QSHE. For the armchair nanoribbon, the QSHE is shown to be stable. We have also derived the real space effective hamiltonian, which demonstrates that the on-site energy and the effective spin orbit coupling strength are strongly enhanced near the ribbon edges. We have shown that the steep rise of the confinement potential thus obtained is responsible for the warping of the $\pi$-edge bands.
Self-similar occurrence of massless Dirac particles in graphene under magnetic field
Jun-Won Rhim,Kwon Park
Physics , 2012, DOI: 10.1103/PhysRevB.86.235411
Abstract: Intricate interplay between the periodicity of the lattice structure and that of the cyclotron motion gives rise to a well-known self-similar fractal structure of the energy eigenvalue, known as the Hofstadter butterfly, for an electron moving in lattice under magnetic field. Evolving from the $n=0$ Landau level, the central band of the Hofstadter butterfly is especially interesting since it may hold a key to the mysteries of the fractional quantum Hall effect observed in graphene. While the entire Hofstadter butterfly can be in principle obtained by solving Harper's equations numerically, the weak-field limit, most relevant for experiment, is intractable due to the fact that the size of the Hamiltonian matrix, that needs to be diagonalized, diverges. In this paper, we develop an effective Hamiltonian method that can be used to provide an accurate analytic description of the central Hofstadter band in the weak-field regime. One of the most important discoveries obtained in this work is that massless Dirac particles always exist inside the central Hofstadter band no matter how small the magnetic flux may become. In other words, with its bandwidth broadened by the lattice effect, the $n=0$ Landau level contains massless Dirac particles within itself. In fact, by carefully analyzing the self-similar recursive pattern of the central Hofstadter band, we conclude that massless Dirac particles should occur under arbitrary magnetic field. As a corollary, the central Hofstadter band also contains a self-similar structure of recursive Landau levels associated with such massless Dirac particles. To assess the experimental feasibility of observing massless Dirac particles inside the central Hofstadter band, we compute the width of the central Hofstadter band as a function of magnetic field in the weak-field regime.
Emergent p-wave Kondo Coupling in Multi-Orbital Bands with Mirror Symmetry Breaking
Jun Won Rhim,Jung Hoon Han
Physics , 2013, DOI: 10.7566/JPSJ.82.104704
Abstract: We examine Kondo effect in the periodic Anderson model for which the conduction band is of multi-orbital character and subject to mirror symmetry breaking field imposed externally. Taking p-orbital-based toy model for analysis, we find the Kondo pairing symmetry of p-wave character emerges self-consistently over some regions of parameter space and filling factor even though only the on-site Kondo hybridization is assumed in the microscopic Hamiltonian. The band structure in the Kondo-hybridized phase becomes nematic, with only two-fold symmetry, due to the p-wave Kondo coupling. The reduced symmetry should be readily observable in spectroscopic or transport measurements for heavy fermion system in a multilayer environment such as successfully grown recently.
Quantum oscillations in the Luttinger model with quadratic band touching: applications to pyrochlore iridates
Jun-Won Rhim,Yong Baek Kim
Physics , 2014, DOI: 10.1103/PhysRevB.91.115124
Abstract: Motivated by recent experiments on Pr2Ir2O7, we provide a theory of quantum oscillations in the Luttinger model with quadratic band touching, modelled for the spin-orbit-coupled conduction electrons in pyrochlore iridates. The magneto- and Hall resistivities are computed for electron- and hole-doped systems, and the corresponding Shubnikov de Haas (SdH) signals are investigated. The SdH signals are characterized by aperiodic behaviors that originate from the unconventional Landau level structures of the Luttinger model near the neutrality point, such as the inter-Landau level crossing, nonuniform Landau level spacings and non-parabolic dispersions along the applied magnetic-field direction. The aperiodic SdH signals observed in the paramagnetic state of Pr2Ir2O7 are shown to be consistent with such behaviors, justifying the use of the Luttinger model and the quadratic band touching spectrum as excellent starting points for physics of pyrochlore iridates. The implications of these results are discussed in light of recent theoretical and experimental devel- opments in these systems.
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