A note on dual giant gravitons in AdS4×CP3AdS_{4}\times \mathbb{CP}^{3}

We study some of the properties of dual giant gravitons - D2-branes wrapped on an $S^{2}\subset AdS_{4}$ - in type IIA string theory on $AdS_{4}\times \mathbb{CP}^{3}$. In particular we confirm that the spectrum of small fluctuations about the giant is both real and independent of the size of the graviton. We also extend previously developed techniques for attaching open strings to giants to this D2-brane giant and focus on two particular limits of the resulting string sigma model: In the pp-wave limit we quantize the string and compute the spectrum of bosonic excitations while in the semiclassical limit, we read off the fast string Polyakov action and comment on the comparison to the Landau-Lifshitz action for the dual open spin chain.Comment: v3 significantly changed: added coupling to RR 1-form and turned on worldvolume gauge field, computed gauge field fluctuation, added comments on closure of the sl(2) sector and re-written to improve clarity. This version published in JHE

Studies on association of arbuscular mycorrhizal fungi with gluconacetobacter diazotrophicus and its effect on improvement of sorghum bicolor (L.)

Considerable attention has been paid on endophytic diazotrophs in recent times, because of its of ability to fix and transfer fixed nitrogen to the host plant. Arbuscular mycorrhizal (AM) fungi are ubiquitous and play a significant role in improving the growth of plants through better uptake of nutrients, especially phosphorus. Interaction between AM fungi and nitrogen fixing bacteria and its impact on the host plant has been studied in several instances. In the present study, an attempt has been made to know the combining ability of G.diazotrophicus with AM fungi on S.bicolor. Spores of ten species of AM fungi were isolated from the rhizosphere soils of S.bicolor from different localities of Madurai and Sivagangai districts of Tamil Nadu. G.diazotrophicus was isolated from stem tissues of sugarcane (Saccharrum officinarum L.) from Madurai districts. The AM fungi in association with G.diazotrophicus were evaluated on the basis of root colonization, fresh and drymatter yield, N, P, soluble sugars and photosynthetic pigments in leaves of S.bicolor. Fresh weight and dry weight was significantly higher in dual inoculated plants. The highest values were recorded with Glomus fasciculatum + G.diazotrophicus combination. AM fungal infection was significantly higher in dual inoculated plants. N concentration was significantly increased by G.diazotrophicus even more in association with the efficient fungal strains. Dual inoculated plants showed a significant increase in P, soluble sugars, photosynthetic pigments in leaves was observed in G.diazotrophicus + Glomus fasciculatum combination. Such morphological modification may enhance water and nutrient uptake. Our results confirm the importance of studying plant-microbial interrelationship to provide useful information for agricultural system management

Emergence of the fuzzy horizon through gravitational collapse

For a large enough Schwarzschild black hole, the horizon is a region of space where gravitational forces are weak; yet it is also a region leading to numerous puzzles connected to stringy physics. In this work, we analyze the process of gravitational collapse and black hole formation in the context of light-cone M theory. We find that, as a shell of matter contracts and is about to reveal a black hole horizon, it undergoes a thermodynamic phase transition. This involves the binding of D0 branes into D2's, and the new phase leads to large membranes of the size of the horizon. These in turn can sustain their large size through back-reaction and the dielectric Myers effect - realizing the fuzzball proposal of Mathur and the Matrix black hole of M(atrix) theory. The physics responsible for this phenomenon lies in strongly coupled 2+1 dimensional non-commutative dynamics. The phenomenon has a universal character and appears generic.Comment: 24 pages, 4 figures; v2: minor clarifications, citations adde

Preliminary Investigation into Modeling The Damage to Carbon Fibre Composites Due to the Thermo-electric Effects of a Lightning Strikes

The impact of a lightning strike causes a short high electrical current burst through Carbon Fibre Composites (CFC). Due to the electrical properties of CFC the large current leads to a rapid heating of the surrounding impact area which degrades and damages the CFC. It is therefore necessary to study in detail the thermal response and possible degradation processes caused to CFC. The degradation takes place in two ways, firstly via direct mechanical fracture due to the thermal expansion of the CFC and secondly via thermo-chemical processes (phase change and pyrolysis) at high temperatures. The main objective of this work is to construct a numerical model of the major physical processes involved, and to understand the correlation between the damage mechanisms and the damage witnessed in modern CFC. For this work we are only considering the thermo-chemical degradation of CFC. Bespoke numerical models have been constructed to predict the extent of the damage caused by the two thermo-chemical processes separately (e.g. a model for phase change and a model for pyrolysis). The numerical model predictions have then been verified experimental by decoupling of the damage mechanisms, e.g. the real Joule heating from a lightning strike is replaced by a high power laser beam acting on composite surface. This was done to simplify the physical processes which occur when a sample is damaged. The experimentally damaged samples were then investigated using X-ray tomography to determine the physical extent of the damage. The experimental results are then compared with the numerical predictions by considering the physical extent of the polymer removal. The extent of polymer removal predicted by the numerical model, solving for pyrolysis, gave a reasonable agreement with the damage seen in the experimental sample. Furthermore the numerical model predicts that the damage caused by polymer phase change has a minimal contribution to the overall extent of the damage

Towards a Realization of the Condensed-Matter/Gravity Correspondence in String Theory via Consistent Abelian Truncation

We present an embedding of the 3-dimensional relativistic Landau-Ginzburg model for condensed matter systems in an $\mathcal{N}=6$, $U(N)\times U(N)$ Chern-Simons-matter theory (the ABJM model) by consistently truncating the latter to an abelian effective field theory encoding the collective dynamics of ${\cal O}(N)$ of the ${\cal O}(N^2)$ modes. In fact, depending on the VEV on one of the ABJM scalars, a mass deformation parameter $\mu$ and the Chern-Simons level number $k$, our abelianization prescription allows us to interpolate between the abelian Higgs model with its usual multi-vortex solutions and a $\phi^4$ theory. We sketch a simple condensed matter model that reproduces all the salient features of the abelianization. In this context, the abelianization can be interpreted as giving a dimensional reduction from four dimensions.Comment: 4 pages, revtex; reference added, typo corrected; added clarifying paragraphs at end of introduction and on pages 3-4. Version accepted to PR

Thaan Vuzha Nilam Tharisu: the land without a farmer becomes barren

This report forms a part of the international research project on policy and sustainable agriculture, Policies that Work for Sustainable Agriculture and Regenerated Rural Economies. The report details the findings of one of the constituent studies, undertaken by an Indian NGO, the Society for People's Education and Economic Change (SPEECH). The Importance of this project is that it concentrated on rainfed rather than irrigated agriculture - i.e. the sharp end of rural development in India, and that the focus was very much on the micro-level, looking at policy as seen from the ground. One of the recurring themes throughout the research was the importance of appreciating people as individuals, and in this spirit some of the personal qualities of the research team are shared. The research covers events in sites in the Virudhunagar district of Tamilnadu: Tiruchuli Panchayat Union and the Villur chain of tanks. This is an essentially rural area, where the need for sustainable forms of agriculture and rural livelihoods is clear. The political landscape is fractured and complex (§2.3), and the officials with the responsibility of implementing policy face significant obstacles and disincentives in doing so in response to the needs of local communities