The production of traditional cool season grasses in temperate regions is becoming hampered during summer seasons due to water deficit. Thus, incorporating water use efficient warm season annual grasses are generally considered to fill the gap of summer season forage reduction that would offer considerable flexibility and adaptability to respond to forage demand. Teff (Eragrostis teff Zuccagni) Trotter) is, a C4 drought tolerant warm season annual grass primarily grown for grain production, recently gaining interest for forage production particularly during summer season. Previous reports have showed that teff is palatable and has comparable forage biomass and feed quality as compared to other warm season annual grasses which would make it an alternative forage. However, the available data are not comprehensive to explore the potential of teff as forage, hence further assessment of genotype variability and performance along with compatibility study of teff with forage production system of specific environment is key for future utilization.

Animals must maintain proper balance between energy intake and expenditure. Recently, we descovered the enzymaticco-factor tetrahydrobiopterin (BH4) inhibits feeding in Drosophila. BH4 biosynthesis requires the sequential action of theconserved enzymes Punch, Purple, and Sepiapterin Reductase (Sptr). Although we observe increased feeding upon lossof Punch and Purple in the adult fat body, loss of Sptr must occur in the brain. We found Sptr expression is requiredin four adult brain neurons that express NPF, the fly homologue of the vertebrate appetite regulator NPY. Mechanistically,we found BH4 deficiency reduces NPF levels, while excess BH4 increases NPF accumulation without altering its expression.

동물들은 항상성 유지를 위해서 지방에 축적된 에너지의 양을 판단하고 섭식량을 조절한다고 알려져 있으나 그 조절 메카니즘은 아직 확실히 알려져있지 않다. 본 연구에서는 노랑초파리로 지방세포에서 섭식조절과 관련된 유전자를 찾기 위해 mRNA의 과발현을 이용한 1차 스크리닝(screening)과 RNAi를 이용한 2차 스크리닝을 수행하여 지방세포에서 발현하는 유전자 purple이 섭식조절과 관련이 있다는 것을 확인하였다. 유전자 purple은 조효소인 tetrahydrobiopterin (BH4)의 생합성에 관여하는 유전자인데, 연구결과 BH4생합성에 관련된 다른 유전자인 Punch와 Sepiapterin Reductase (Sptr) 뿐만 아니라 BH4도 섭식행동을 조절하는데에 관여한다는 것을 밝혀냈다. 흥미로운 사실은 Punch와 purple은 지방에서 발현되어야 하는 반면 Sptr은 뇌에서 발현되어 섭식행동을 조절한다는 사실이다. 추가연구를 통해 BH4가 섭식에 관련된 뉴런인 neuropeptide F (NPF)을 억제하여 섭식억제가 이루어지는 사실을 확인하였다. 본 연구는 새로운 유형의 섭식억제제 개발에 기초적인 정보를 제공할 것으로 보인다.

Massive stars are some of the most in uential objects in the Universe, shaping the evolution of galaxies, creating chemical elements and hence shaping the evolution of the Universe. However, the processes by which they form and how they shape their environment during their birth processes are not well understood. We use NH3 data from "The H2O Southern Galactic Plane Survey" (HOPS) survey to dene the positions of dense cores/clumps of gas in the southern Galactic plane that are likely to form stars. Then, using data from "The Millimetre Astronomy Legacy Team 90 GHz" (MALT90) survey, we search for the presence of infall and out ow associated with these cores. We subsequently use the "3D Molecular Line Radiative Transfer Code" (MOLLIE) to constrain properties of the infall and outflow, such as velocity and mass flow. The aim of the project is to determine how common infall and outflow are in star forming cores, and therefore to provide valuable constraints on the timescales and physical process involved in massive star formation. Preliminary results are presented here.

We introduce a method of identifying evidence of shocks in the X-ray emitting gas in clusters of galaxies. Using information from synthetic observations of simulated clusters, we do a blind search of the synthetic image plane. The locations of likely shocks found using this method closely match those of shocks identified in the simulation hydrodynamic data. Though this method assumes nothing about the geometry of the shocks, the general distribution of shocks as a function of Mach number in the cluster hydrodynamic data can be extracted via this method. Characterization of the cluster shock distribution is critical to understanding production of cosmic rays in clusters and the use of shocks as dynamical tracers.

I briefly review the current theoretical status of the origins of ultrahigh energy cosmic rays with special emphasis on models associated with galaxy clusters. Some basic constraints on models are laid out, including those that apply both to so-called 'top-down' and 'bottom-up' models. The origins of these UHECRs remain an enigma; no model stands out as a clear favorite. Large scale structure formation shocks, while very attractive conceptually in this context, are unlikely to be able to accelerate particles to energies much above 1018eV. Terminal shocks in relativistic AGN jets seem to be more viable candidates physically, but suffer from their rarity in the local universe. Several other, representative, models are outlined for comparison.

Cosmological shocks form as an inevitable consequence of gravitational collapse during the large scale structure formation and cosmic-rays (CRs) are known to be accelerated at collisionless shocks via diffusive shock acceleration (DSA). We have calculated the evolution of CR modified shocks for a wide range of shock Mach numbers and shock speeds through numerical simulations of DSA in 1D quasi-parallel plane shocks. The simulations include thermal leakage injection of seed CRs, as well as pre-existing, upstream CR populations. Bohm-like diffusion is assumed. We show that CR modified shocks evolve to time-asymptotic states by the time injected particles are accelerated to moderately relativistic energies (p/mc ≳ 1), and that two shocks with the same Mach number, but with different shock speeds, evolve qualitatively similarly when the results are presented in terms of a characteristic diffusion length and diffusion time. We find that 10-4 - 10-3 of the particles passed through the shock are accelerated to form the CR population, and the injection rate is higher for shocks with higher Mach number. The CR acceleration efficiency increases with shock Mach number, but it asymptotes to ~50% in high Mach number shocks, regardless of the injection rate and upstream CR pressure. On the other hand, in moderate strength shocks (Ms ≲ 5), the pre-existing CRs increase the overall CR energy. We conclude that the CR acceleration at cosmological shocks is efficient enough to lead to significant nonlinear modifications to the shock structures.

Cosmological hydrodynamic simulations of large scale structure in the universe have shown that accretion shocks and merger shocks form due to flow motions associated with the gravitational collapse of nonlinear structures. Estimated speed and curvature radius of these shocks could be as large as a few 1000 km/s and several Mpc, respectively. According to the diffusive shock acceleration theory, populations of cosmic-ray particles can be injected and accelerated to very high energy by astrophysical shocks in tenuous plasmas. In order to explore the cosmic ray acceleration at the cosmic shocks, we have performed nonlinear numerical simulations of cosmic ray (CR) modified shocks with the newly developed CRASH (Cosmic Ray Amr SHock) numerical code. We adopted the Bohm diffusion model for CRs, based on the hypothesis that strong Alfven waves are self-generated by streaming CRs. The shock formation simulation includes a plasma-physics-based 'injection' model that transfers a small proportion of the thermal proton flux through the shock into low energy CRs for acceleration there. We found that, for strong accretion shocks, CRs can absorb most of shock kinetic energy and the accretion shock speed is reduced up to 20%, compared to pure gas dynamic shocks. For merger shocks with small Mach numbers, however, the energy transfer to CRs is only about 10-20% with an associated CR particle fraction of 10-3. Nonlinear feedback due to the CR pressure is insignificant in the latter shocks. Although detailed results depend on models for the particle diffusion and injection, these calculations show that cosmic shocks in large scale structure could provide acceleration sites of extragalactic cosmic rays of the highest energy.

Compressible, magnetohydrodynamic (MHD) turbulence in two dimension is studied through high-resolution, numerical simulations with the isothermal equation of state. First, hydrodynamic turbulence with Mach number (M)rms ~ 1 is generated by enforcing a random force. Next, initial, uniform magnetic field of various strengths with Alfvenic Mach number Ma ≫ 1 is added. Then, the simulations are followed until MHD turbulence is fully developed. Such turbulence is expected to exist in a variety of astrophysical environments including clusters of galaxies. Although no dissipation is included explicitly in our simulations, truncation errors produce dissipation which induces numerical resistivity. It mimics a hyper-resistivity in our second-order accurate code. After saturation, the resulting flows are categorized as SF (strong field), WF (weak field), and VWF (very weak field) classes respectively, depending on the average magnetic field strength described with Alfvenic Mach number, (Ma)rms ~1, (Ma)rms≥1, and (Ma)rms ≫ 1. The characteristics of each class are discussed.

Cosmic-ray acceleration, although physically important in many astrophysical contexts, is difficult to incorporate into numerical models,. because it involves microphysics that is generally far from thermodynamic equilibrium, and also because the length and time scales for that physics typically range over many orders of magnitude, reflecting the huge range of particle rigidities that must be represented. The most common accelerator models are stochastic in nature and involve nonequilibrium plasma properties that are also often poorly understood. Still, nature clearly finds a way to produce simple, robust and almost scale-free energy distributions for the cosmic-rays. Their importance has inspired a number of approaches to examining the production and transport of cosmic-ray particles in numerical simulations. I offer here a brief comparison of some of the methods that have been introduced.

Rarefied cosmic plasmas generally do not achieve thermodynamic equilibria, and a natural consequence of this is the presence of a significant population of charged particles with energies well above those of the bulk population. These are exemplified by the galactic cosmic rays, but the importance of these high energy populations extends well beyond that context. I review here some of the basic issues associated with the propagation and acceleration of cosmic rays, especially in the context of collisionless plasma shocks.

Coldwell alkaline complex adjacent to the north of Lake Superior in Ontario, Canada is an isolated plutonic body composed chiefly of syenite and gabbros and Archean metamorphic rocks intruded by above mentioned igneous rocks. A pegmatite swarm is developed in olivine gabbro, a member of the complex. Zonal distribution is found in most of pegmatites and is composed of three zones, that is, leucocratic fine-grained zone of anorthosite, melanocratic fine-grained zone of gabbronorite and pyroxenite and coarse-grained zone of gabbronorite. The mean grain size of the rock forming minerals in fine-grained zone is 0.27㎜ and that of coarse-grained zone 10.4㎜. An content of most plagioclases is in the range from An50 to An70 indicating that the pegmatite is mafic pegmatite. In a grain of plagioclase, An content decreases gradually from core to margin. Paragenetic sequence of main minerals in pegmatite is plagioclase, olivine, pyroxene, hornblende, biotite and opaque mineral from the earlier stage. Mineralogy in pegmatite is similar to that of the country rock, so it can be classified as simple and pure pegmatite. Fine-grained zone might be formed by rapid crystallization with high viscosity caused by rapid reduction in P_(H₂O) when coexisting vapor phase is suddenly released and raising the sotidus and liquidus temperatures abruptly. Coarse-grained zone is probably formed by high diffusion rate and low viscosity caused by depolymerization, formation of aqueous phase and decrease of solidus temperature. The rate of increase in viscosity caused by cooling of magma from the magmatic stage and high content of SiO₂ is ignorable compared with the rate of decrease in viscosity caused by concentration of water.