Dynamical quantum phase transitions in Weyl semimetals

The quench dynamics in type-I inversion symmetric Weyl semimetals (WSM) are explored in this work which, due to the form of the Hamiltonian, may be readily extended to two-dimensional Chern insulators. We analyze the role of equilibrium topological properties characterized by the Chern number of the pre-quench ground state in dictating the non-equilibrium dynamics of the system, specifically, the emergence of dynamical quantum phase transitions (DQPT). By investigating the ground state fidelity, it is found that a change in the signed Chern number constitutes a sufficient but not necessary condition for the occurrence of DQPTs. Depending on the ratio of the transverse and longitudinal hopping parameters, DQPTs may also be observed for quenches lying entirely within the initial Chern phase. Additionally, we analyze the zeros of the boundary partition function discovering that while the zeros generally form two-dimensional structures resulting in one-dimensional critical times, infinitesimal quenches may lead to one-dimensional zeros with zero-dimensional critical times provided the quench distance scales appropriately with the system size. This is strikingly manifested in the nature of non-analyticies of the dynamical free energy, revealing a logarithmic singularity. In addition, following recent experimental advances in observing the dynamical Fisher zeros of the Loschmidt overlap amplitude through azimuthal Bloch phase vortices by Bloch-state tomography, we rigorously investigate the same in WSMs. Finally, we establish the relationship between the dimension of the critical times and the presence of dynamical vortices, demonstrating that only one-dimensional critical times arising from two-dimensional manifolds of zeros of the boundary partition function lead to dynamical vortices.Comment: 15 pages, 9 figure

ASR: Ari Screen Reader for Website Applications

With the current technological advancements, an extraordinary amount of data is available over the Internet. 59% of the world population, which accounts to 4.57 billion people have access to the Internet and retrieve or generate a variety of data and information through it. Also, 15% of the world population has some forms of disability, and this comes with certain accessibility issues that restrict them from properly and fully make use of various websites. Most of the websites, accessed by the general public, are now developed so that a person with a disability can access and perform all the tasks using screen readers. However, they do not provide default screen readers alongside the web content. This thesis describes how a screen reader tool can be integrated with a website and help the users’ access the website’s information. In particular, the proposed Ari Screen Reader (ASR) helps users navigate web pages using a web browser without the use of external screen readers. Also, ASR enhances the user experience of both disabled and non-disabled users. This thesis includes an overview of web accessibility, a brief survey of related research and development efforts, a user study that helped motivate the work presented here, details of software specification and design, examples of ASR use, and a feature-based comparison with similar existing tools. Conclusions and pointers to several directions of future work are also provided

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Not AvailableThe Brackishwater aquaculture sector in India has for several decades been dominated by a single species or multiple species of shrimps. Though several options for farming finfish varieties had been made available, farmers preferred to culture shrimp for its ease in culture, marketing and profitability. With increasing global competition in seafood production and supply, causing unstable markets and unpredictable prices, as well as new and emerging diseases causing widespread production issues in the sector, it is only imperative that, for its long term sustenance, the sector seriously consider species diversification and adopt innovative practices and technologies to farm multiple brackishwater species along the Indian coastal areasNot Availabl

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Not AvailableAn integrated multi-trophic aquaculture (IMTA) model involving mullets (Mugil cephalus and Liza parsia) and tiger shrimp (Penaeus monodon) as fed-species, and estuarine oyster (Crassostrea cuttackensis) and seaweed, Enteromorpha spp. as extractive species was evaluated as a viable aquaculture option in brackishwater of the Indian Sundarban. A 150-day field experiment was conducted in six brackishwater ponds (600 m2 each). There were two randomly assigned groups, IMTA and polyculture (control) with three replicate ponds. Ponds under IMTA were stocked with mullets and tiger shrimp at 10000 and 30000 no./ha, respectively, C. cuttackensis at 1600 no./ha suspended with a basket in the water column and Enteromorpha spp. at 200 kg biomass/ha. Control ponds were stocked with mullets and shrimp at the same densities to that of IMTA, and devoid of oyster and seaweed. A common low-cost polyculture feed was provided to fishes and shrimp. Mullets attained a significantly higher growth (p <0.05) in the IMTA system compared to that of control ponds, whereas tiger shrimp had insignificantly higher growth in IMTA than in control. Significantly higher production of 1707 kg/ha (19% higher) with better water quality was obtained in IMTA system compared to that of control ponds (1434 kg/ha) (p <0.05). There was a significant reduction in apparent feed conversion ratio by 22%, and an increase in net income by 69% and benefit-cost ratio by 30% in the IMTA system than that of the control. Moreover, for the first time the estuarine oyster, C. cuttackensis was used as an extractive species in brackishwater IMTA system. From an indoor trial, it was observed that this oyster species has high water filtration capacity to remove suspended matters, including planktons. This preliminary experiment indicates the application of IMTA concept in brackishwater as a viable environment-friendly option and warrants further refinement for species combination with the economic viability and environmental suitability.Not Availabl

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Not AvailableSuccessful aquaculture largely depends on the availability of sufficient quality seed at the required time. Availability of quality seed from natural sources is always erratic and undependable. Moreover collection of wild seed will deplete the natural fishery. Almost all of the cultivable brackishwater finfishes do not breed in captivity even though they attain gonadal maturity. Hence it has become necessary to go for induced breeding either by reproductive hormonal or environmental manipulation. Artificial spawning was first achieved in Italy during 1930 in striped mullet. Use of hormones to induce fish to spawn was started in Brazil in 1932. Compared to the advancement made in the breeding and seed production of freshwater fishes, the technology development in brackishwater fishes especially in India is far behind and this is to some extent are due to the non-availability of facilities for the development of captive broodstock and lack of expertise.Not Availabl

Aquaculture

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Not AvailableThe Spotted Scat (Scatophagus argus), an important euryhaline fish inhabiting mangrove and coastal regions of Indo-Pacific waters, is both an ornamental and food fish in India. Detailed insight into maturation of Spotted Scat when maintained in aquaculture systems, therefore, needs to be elucidated. Lack of information on annual maturation dynamics of female scat collected from their natural habitat and reared in earthen ponds is the basis of this study. Oocytes were classified into five developmental stages: pre-vitellogenic, vitellogenic, late-vitellogenic, ripe, and follicular atresia. Ovarian maturity stages were subsequently categorized as immature (Stage 1), vitellogenesis (Stage 2), maturing (Stage 3), mature (Stage 4), and spent (Stage 5). In oocytes in primary, secondary and tertiary yolk stages, there are greater concentrations of E2 in vitellogenic females between March and June. Significant increases of E2, T, and 17-OHP paralleled the increase of diameter of late–vitellogenic oocytes in maturing females during July. The completion of vitellogenesis and initiation of germinal vesicle migration in the cytoplasm were evident in mature females (Stage 4) with a decreasing trend of sex steroids in and subsequent to the month of August. There were 50 % of oocytes in the final oocyte maturation stage (FOM) (490–620 μm) until completion of Stage 4 in September. The results of this study indicate there is complete ovarian maturation in female scats captured in their natural habitat and maintained in an earthen pond, which may be important information for hatchery management for induction of spawning of Spotted Scat in aquaculture systems.Not Availabl

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Not AvailableImpact of osmoregulation on plasma sex steroid levels and gonadal histo-architecture was monitored to elucidate the effects of deviation from habitat salinity on gonadal recrudescence in an active reproductive season of an euryhaline fish Etroplus suratensis (pearlspot). Fish were maintained in three different salinities of 0 ppt Fresh Water (FW), 15 ppt Brackish Water (BW) and 30 ppt Sea Water (SW) for a period of 60 days. Plasma osmolality values were found to be significantly highest in SW-acclimated fish accompanied by highest levels of plasma K⁺ and Cl¯ ions. The progress of gonadal recrudescence was higher in BW followed by FW and SW as evident from the cellular features of gonads and increased level of plasma sex steroids, such as, in case of female and 11-keto Testosterone and Testosterone in case of males. Plasma cortisol levels were comparatively higher in fish of both sexes in SW group. Significantly high levels of cortisol in SW suggest its role in hypo-osmoregulation and associated stress. This study clearly reveals that salinity changes during the active reproductive phase can suppress the steroid-mediated gonad recrudescence maximally under hypo-osmoregulation in an euryhaline fish.Not Availabl