5,302 research outputs found
Effects of Paclobutrazol and its method of application on the growth and transpiration of Acacia Mangium Seedlings
Ten-week-old potted A. mangium seedlings were subjected to a growth retardant, paclobutrazol (PP333), at
concentrations of 0, 0.5, 1, 4 and 12 gil. Four methods of application were tested namely S, soil drenching at
week 0; F1, foliar spray (potting soil protected from chemical) at week 0; F2, foliar spray (potting soil protected
from chemical) at week 0 and 6; and S+F, soil and foliar spray (potting soil exposed to chemical spray) at week
O. Plants were harvested after 12 weeks for various growth measurements. Height and leaf area increments,
transpiration and stomatal conductance were monitored at weekly intervals. Paclobutrazol was found to be
effective in reducing root and shoot growth, transpiration and stomatal conductance of the seedlings. Treated
plants had higher root to shoot ratios. The effects of the chemical increased with increasing concentration and
frequency of application for the foliar spray. The chemical was most effective when applied through the soil either
l7y drenching (S) or soil and foliar spray (S+F)
Children of Immigrants: Healthy Beginnings Derailed by Food Insecurity
Children of immigrants are the fastest growing child population in the United States. More than 20 percent of children under age six have immigrant parents; approximately 93 percent of these children are American citizens.Of the children who are non-citizens, two-thirds will grow up to become citizens, playing a critical role in our nation's future
Using participatory design and visual narrative inquiry to investigate researchers’ data challenges and recommendations for library research data services
Purpose – The purpose of this paper is to report on an information gathering study on users’ research data-related challenges and proposals for library research data services (RDS). This study probes how early career researchers visually conceptualize the research process in their disciplines, their self-reported research data challenges, and their recommendations for library RDS. Design/methodology/approach – Two focus group sessions were undertaken with a total of eight early career researchers. Adopting the visual narrative inquiry method, the participants were asked to sketch the general research process in their domain. The individuals’ illustrations of the research process were then used as the basis for reflecting on their data-related needs and potential RDS that would assist them during the research process. Findings – Participants presented a research process that was more personal and, in most cases, more imperfect than the research lifecycle models that academic libraries are increasingly using for RDS development and communication. The authors present their data-related challenges, which included data access barriers, low knowledge of best practices for research data management, the need for a deeper understanding of post-publication impact, and inconsistent awareness of existing library and institution RDS. The authors outline RDS recommendations that participants proposed, which included a web-based tools, customized training sessions, and “distilled” guides to research data best practices. Practical implications – The study flagged users’ gaps in understandings of existing library and institutional RDS, suggesting that there may be an opportunity to engage users in the design of communications plans for services. The findings from this user study will inform the development of RDS at the institution. Originality/value – This paper puts forth a methodological approach that academic libraries can adapt for understanding users’ needs and user-generated design solutions
Fiber Optic Tactical Local Network (FOTLAN)
A 100 Mbit/s FDDI (fiber distributed data interface) network interface unit is described that supports real-time data, voice and video. Its high-speed interrupt-driven hardware architecture efficiently manages stream and packet data transfer to the FDDI network. Other enhancements include modular single-mode laser-diode fiber optic links to maximize node spacing, optic bypass switches for increased fault tolerance, and a hardware performance monitor to gather real-time network diagnostics
Metal-insulator transition from combined disorder and interaction effects in Hubbard-like electronic lattice models with random hopping
We uncover a disorder-driven instability in the diffusive Fermi liquid phase
of a class of many-fermion systems, indicative of a metal-insulator transition
of first order type, which arises solely from the competition between quenched
disorder and interparticle interactions. Our result is expected to be relevant
for sufficiently strong disorder in d = 3 spatial dimensions. Specifically, we
study a class of half-filled, Hubbard-like models for spinless fermions with
(complex) random hopping and short-ranged interactions on bipartite lattices,
in d > 1. In a given realization, the hopping disorder breaks time reversal
invariance, but preserves the special ``nesting'' symmetry responsible for the
charge density wave instability of the ballistic Fermi liquid. This disorder
may arise, e.g., from the application of a random magnetic field to the
otherwise clean model. We derive a low energy effective field theory
description for this class of disordered, interacting fermion systems, which
takes the form of a Finkel'stein non-linear sigma model [A. M. Finkel'stein,
Zh. Eksp. Teor. Fiz. 84, 168 (1983), Sov. Phys. JETP 57, 97 (1983)]. We analyze
the Finkel'stein sigma model using a perturbative, one-loop renormalization
group analysis controlled via an epsilon-expansion in d = 2 + epsilon
dimensions. We find that, in d = 2 dimensions, the interactions destabilize the
conducting phase known to exist in the disordered, non-interacting system. The
metal-insulator transition that we identify in d > 2 dimensions occurs for
disorder strengths of order epsilon, and is therefore perturbatively accessible
for epsilon << 1. We emphasize that the disordered system has no localized
phase in the absence of interactions, so that a localized phase, and the
transition into it, can only appear due to the presence of the interactions.Comment: 47 pages, 25 figures; submitted to Phys. Rev. B. Long version of
arXiv:cond-mat/060757
Refined conformal spectra in the dimer model
Working with Lieb's transfer matrix for the dimer model, we point out that
the full set of dimer configurations may be partitioned into disjoint subsets
(sectors) closed under the action of the transfer matrix. These sectors are
labelled by an integer or half-integer quantum number we call the variation
index. In the continuum scaling limit, each sector gives rise to a
representation of the Virasoro algebra. We determine the corresponding
conformal partition functions and their finitizations, and observe an
intriguing link to the Ramond and Neveu-Schwarz sectors of the critical dense
polymer model as described by a conformal field theory with central charge
c=-2.Comment: 44 page
Topological Surface States and Dirac point tuning in ternary Bi2Te2Se class of topological insulators
Using angle-resolved photoemission spectroscopy, we report electronic
structure for representative members of ternary topological insulators. We show
that several members of this family, such as Bi2Se2Te, Bi2Te2Se, and GeBi2Te4,
exhibit a singly degenerate Dirac-like surface state, while Bi2Se2S is a fully
gapped insulator with no measurable surface state. One of these compounds,
Bi2Se2Te, shows tunable surface state dispersion upon its electronic alloying
with Sb (SbxBi2-xSe2Te series). Other members of the ternary family such as
GeBi2Te4 and BiTe1.5S1.5 show an in-gap surface Dirac point, the former of
which has been predicted to show nonzero weak topological invariants such as
(1;111); thus belonging to a different topological class than BiTe1.5S1.5. The
measured band structure presented here will be a valuable guide for
interpreting transport, thermoelectric, and thermopower measurements on these
compounds. The unique surface band topology observed in these compounds
contributes towards identifying designer materials with desired flexibility
needed for thermoelectric and spintronic device fabrication.Comment: 9 pages, 6 figures; Related results at
http://online.kitp.ucsb.edu/online/topomat11/hasan
Explicit characterization of the identity configuration in an Abelian Sandpile Model
Since the work of Creutz, identifying the group identities for the Abelian
Sandpile Model (ASM) on a given lattice is a puzzling issue: on rectangular
portions of Z^2 complex quasi-self-similar structures arise. We study the ASM
on the square lattice, in different geometries, and a variant with directed
edges. Cylinders, through their extra symmetry, allow an easy determination of
the identity, which is a homogeneous function. The directed variant on square
geometry shows a remarkable exact structure, asymptotically self-similar.Comment: 11 pages, 8 figure
Disorder-induced Majorana metal in interacting non-Abelian anyon systems
We demonstrate that a thermal metal of Majorana fermions forms in a
two-dimensional system of interacting non-Abelian (Ising) anyons in the
presence of moderate disorder. This bulk metallic phase arises in the
quantum Hall state when disorder pins the anyonic quasiparticles. More
generally, it naturally occurs for various proposed systems supporting Majorana
fermion zero modes when disorder induces the random pinning of a finite density
of vortices. This includes all two-dimensional topological superconductors in
so-called symmetry class D. A distinct experimental signature of the thermal
metal phase is the presence of bulk heat transport down to zero temperature.Comment: 4 pages, 6 figure
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