Topology- and symmetry-protected domain wall conduction in quantum Hall nematics

We consider domain walls in nematic quantum Hall ferromagnets predicted to form in multivalley semiconductors, recently probed by scanning tunnelling microscopy experiments on Bi(111) surfaces. We show that the domain wall properties depend sensitively on the filling factor $\nu$ of the underlying (integer) quantum Hall states. For $\nu=1$ and in the absence of impurity scattering we argue that the wall hosts a single-channel Luttinger liquid whose gaplessness is a consequence of valley and charge conservation. For $\nu=2$, it supports a two-channel Luttinger liquid, which for sufficiently strong interactions enters a symmetry-preserving thermal metal phase with a charge gap coexisting with gapless neutral intervalley modes. The domain wall physics in this state is identical to that of a bosonic topological insulator protected by $U(1)\times U(1)$ symmetry, and we provide a formal mapping between these problems. We discuss other unusual properties and experimental signatures of these `anomalous' one-dimensional systems.Comment: 11 pages, 3 figures, published versio

Performance Rubrics for Robustness Evaluation of Web Mutation Operators

Web Applications are the predominant medium for not only business enterprises but also for service-based sector to establish and continue their online presence. However, the robustness of web application is mandatory in seamless interaction with customers for achieving sustainable business. Intruders and unethical hackers keep trying to gain unauthentic access to the web applications and hence it is more necessary for the web application to be resistant against any such attacks. The strength of a web application is indirectly responsible for gaining customer confidence leading to repeat business as well as attracting new customers for profitable longer run. Once the web application gains credibility it is bound to run successfully. In the current work, an attempt has been made to assess the robustness of mutation operators used to test web applications is made. A few rubrics have been proposed to ascertain the strength of projected mutation operators verified on some sample open-source web applications. The functional attributes of a web application are the functionalities offered by the web application. The non-functional attributes of a typical web application are security, performance, availability. Here, web applications are challenged against the afore mentioned non-functional attributes using rubrics like uniformity, uniqueness, reliability, unpredictability, and entropy. A comprehensive analysis has been made for the robustness of the projected web operators against the designed and formulated rubrics

DESIGN, OPTIMIZATION AND EVALUATION OF IBUPROFEN FAST DISSOLVING TABLETS EMPLOYING STARCH PHTHALATE-A NOVEL SUPERDISINTEGRANT

Objective: The objective of the present research was to prepare starch phthalate (a novel super disintegrant) and to optimize and formulate ibuprofen fast dissolving tablets employing 23factorial design using starch phthalate as super disintegrant. Methods: Drug excipient compatibility studies like Fourier-transform infrared spectroscopy (FTIR) and thin-layer chromatography (TLC) studies were carried out to check the drug interaction between ibuprofen and starch phthalate. Direct compression method was used for tablet preparation. Prepared tablets were then evaluated for hardness, friability, drug content, disintegration time, water absorption and wetting time, in vitro dissolution studies. Response surface plots and contour plots were also plotted to know the main effects and interaction effects of independent variables (starch phthalate (A), croscarmellose sodium (B) and crospovidone (C)) on dependent variables (disintegration time and drug dissolution efficiency in 1 minute) and stability studies were also done. Results: Tablets of all formulations were of good quality concerning drug content (100±5%), hardness (3-6 kg/cm2), and friability (less than 0.16%). In all formulations, formulation F5 found to be optimized formulation with least disintegration time 20±0.28 seconds, less wetting time 09±0.12 seconds and enhanced dissolution rate in one minute, i.e., 91.95±0.22 as compared to other formulation. Conclusion: From the research, it was concluded that on combination with crospovidone, starch phthalate enhanced the dissolution efficiency of the drug. Hence, starch phthalate can be used as a novel disintegrant in the manufacturing of fast dissolving tablets

Current Trends in Forest and Environmental Policies in Sri Lanka

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Exploring the Links between Early Life and Young Adulthood Social Experiences and Men’s Later Life Psychobiology as Fathers

Early life cues of environmental harshness and unpredictability have been hypothesized to influence within-species variation in the timing of life history transitions and the dynamics of reproductive strategies, such as investments in mating and parenting. It is also believed that adolescence is an influential developmental period for male reproductive strategies, with those who achieve greater social and sexual success during that period maintaining faster life history strategies into adulthood. If correct, such early life and post-pubertal experiences could also help shape the psychobiological pathways that mediate reproductive strategies, including the well-documented physiological shifts that occur when some men become parents. Drawing on a large sample of Filipino men (n = 417), we evaluate whether men who experienced cues of harshness or unpredictability in childhood or have earlier ages at sexual debut have elevated testosterone (T) as fathers. We also test whether males who experienced a combination of early life experiences of harshness or unpredictability and had earlier ages of sexual debut during adolescence had the most elevated T as fathers. We found that fathers who experienced early life harshness and who engaged in sex at an earlier age had elevated waking T. Among men transitioning to fatherhood across the 4.5-year follow-up period of this study, those who experienced unpredictability and who engaged in sex at an earlier age showed attenuated declines in waking T between baseline and follow-up. Complementing these findings, we found that fathers who first engaged in sex at later ages had greater acute declines in T when they played with their toddlers. We suggest that these patterns could reflect programming effects of sociosexual experiences during the years following the marked biological transitions that accompany puberty, which occur along with the better-studied effects of earlier life exposures to stressors. Overall, our results support the hypothesis that early life circumstances and social and sexual experiences, from early life to young adulthood, help calibrate physiological axes as key mechanisms coordinating dynamic life history strategies

How People Foraging in Urban Greenspace Can Mobilize Social–Ecological Resilience During Covid-19 and Beyond

Informal foraging for food and other natural materials in urban greenspaces is an activity undertaken by many across the world. For some, foraging is a necessary means of survival and livelihood, while for others, it provides cultural and recreational opportunities. In the socioeconomic crises induced by Covid-19, foraging can help communities, especially (but not exclusively) vulnerable people, cope with the impacts of lockdowns, and associated economic decline. In the long run, foraging can help improve social–ecological resilience in urban systems, particularly in response to climate, economic, and disease disruptions. First, we elaborate the ways in which urban foraging can provide immediate relief from the shocks to natural, human, social, physical, and financial capital. We then describe how over time, the livelihood, food, and income diversification brought about by foraging can contribute to preparedness for future uncertainties and gradual change. Cities are increasingly becoming home to the majority of humanity, and urban foraging can be one of the pathways that makes cities more liveable, for humans as well as other species we coexist with. Through the capitals framework, we explore the role foraging could play in addressing issues of biodiversity conservation, culture, and education, good governance and social justice, multifunctional greenspace, and sustainable nature-based livelihoods in urban areas

Bulk crystal growth and electronic characterization of the 3D Dirac Semimetal Na3Bi

High quality hexagon plate-like Na3Bi crystals with large (001) plane surfaces were grown from a molten Na flux. The freshly cleaved crystals were analyzed by low temperature scanning tunneling microscopy (STM) and angle-resolved photoemission spectroscopy (ARPES), allowing for the characterization of the three-dimensional (3D) Dirac semimetal (TDS) behavior and the observation of the topological surface states. Landau levels (LL) were observed, and the energy-momentum relations exhibited a linear dispersion relationship, characteristic of the 3D TDS nature of Na3Bi. In transport measurements on Na3Bi crystals the linear magnetoresistance and Shubnikov-de Haas (SdH) quantum oscillations are observed for the first time.Comment: To be published in a special issue of APL Material

Visualizing Heavy Fermion Confinement and Pauli-Limited Superconductivity in Layered CeCoIn5

Layered material structures play a key role in enhancing electron-electron interactions to create correlated metallic phases that can transform into unconventional superconducting states. The quasi-two-dimensional electronic properties of such compounds are often inferred indirectly through examination of their bulk properties. Here we use scanning tunneling microscopy and spectroscopy to directly probe in cross section the quasi-two-dimensional correlated electronic states of the heavy fermion superconductor CeCoIn5. Our measurements reveal the strong confined nature of heavy quasi-particles, anisotropy of tunneling characteristics, and layer-by-layer modulated behavior of the precursor pseudogap gap phase in this compound. Examining the interlayer coupled superconducting state at low temperatures, we find that the orientation of line defects relative to the d-wave order parameter determines whether in-gap states form due to scattering. Spectroscopic imaging of the anisotropic magnetic vortex cores directly characterizes the short interlayer superconducting coherence length and shows an electronic phase separation near the upper critical in-plane magnetic field, consistent with a Pauli-limited first-order phase transition into a pseudogap phase

Observation of a Nematic Quantum Hall Liquid on the Surface of Bismuth

Nematic quantum fluids with wavefunctions that break the underlying crystalline symmetry can form in interacting electronic systems. We examine the quantum Hall states that arise in high magnetic fields from anisotropic hole pockets on the Bi(111) surface. Spectroscopy performed with a scanning tunneling microscope shows that a combination of local strain and many-body Coulomb interactions lift the six-fold Landau level (LL) degeneracy to form three valley-polarized quantum Hall states. We image the resulting anisotropic LL wavefunctions and show that they have a different orientation for each broken-symmetry state. The wavefunctions correspond precisely to those expected from pairs of hole valleys and provide a direct spatial signature of a nematic electronic phase