7,409 research outputs found
The Sense of Guilt as the Factor Shaping the Form of Waterland and Out of This World
Zadanie pt. „Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki” nr 885/P-DUN/2014 dofinansowane zostało ze środków MNiSW w ramach działalności upowszechniającej nauk
Louise Yelin, From the Margins of the Empire: Christina Stead, Doris Lessing, Nadine Gordimer. Ithaca and London: Cornell University Press, 1998
reviewZadanie pt. „Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki” nr 885/P-DUN/2014 dofinansowane zostało ze środków MNiSW w ramach działalności upowszechniającej nauk
Balanced Combinations of Solutions in Multi-Objective Optimization
For every list of integers x_1, ..., x_m there is some j such that x_1 + ...
+ x_j - x_{j+1} - ... - x_m \approx 0. So the list can be nearly balanced and
for this we only need one alternation between addition and subtraction. But
what if the x_i are k-dimensional integer vectors? Using results from
topological degree theory we show that balancing is still possible, now with k
alternations.
This result is useful in multi-objective optimization, as it allows a
polynomial-time computable balance of two alternatives with conflicting costs.
The application to two multi-objective optimization problems yields the
following results:
- A randomized 1/2-approximation for multi-objective maximum asymmetric
traveling salesman, which improves and simplifies the best known approximation
for this problem.
- A deterministic 1/2-approximation for multi-objective maximum weighted
satisfiability
Simulations of Contrail Optical Properties and Radiative Forcing for Various Crystal Shapes
The aim of this study is to investigate the sensitivity of radiative-forcing computations to various contrail
crystal shape models. Contrail optical properties in the shortwave and longwave ranges are derived using
a ray-tracing geometric method and the discrete dipole approximation method, respectively. Both methods
present good correspondence of the single-scattering albedo and the asymmetry parameter in a transition
range (3–8 µm). There are substantial differences in single-scattering properties among 10 crystal models
investigated here (e.g., hexagonal columns and plates with different aspect ratios, and spherical particles). The
single-scattering albedo and the asymmetry parameter both vary by up to 0.1 among various crystal shapes.
The computed single-scattering properties are incorporated in the moderate-resolution atmospheric radiance
and transmittance model(MODTRAN) radiative transfer code to simulate solar and infrared fluxes at the top
of the atmosphere. Particle shapes have a strong impact on the contrail radiative forcing in both the shortwave
and longwave ranges. The differences in the net radiative forcing among optical models reach 50% with
respect to the mean model value. The hexagonal-column and hexagonal-plate particles show the smallest net
radiative forcing, and the largest forcing is obtained for the spheres. The balance between the shortwave
forcing and longwave forcing is highly sensitive with respect to the assumed crystal shape and may even
change the sign of the net forcing. The optical depth at which the mean diurnal radiative forcing changes sign
from positive to negative varies from 4.5 to 10 for a surface albedo of 0.2 and from 2 to 6.5 for a surface albedo
of 0.05. Contrails are probably never that optically thick (except for some aged contrail cirrus), however, and
so will not have a cooling effect on climate
Surfaces of Нigh-Tс Superconductors Studied by Means of the Scanning Tunneling Microscope
Observations of the natural surface of BiSrCaCu₂Oₓ sintered ceramics applying the
scanning tunneling microscope are reported. Measurements were performed in air at room
temperature. It can be deduced from the surface images, on which the growth steps are visible with
heights corresponding to the dimension of the unit cell along the c-axis or its multiples, that the bulk
orthorhombic structure extends to the surface. The surface investigated is rather clean, inert and
metallic in nature. It can be identified as the Bi-O layer.Zadanie pt. Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki nr 885/P-DUN/2014 zostało dofinansowane ze środków MNiSW w ramach działalności upowszechniającej naukę
Theoretical study of triaxial shapes of neutron-rich Mo and Ru nuclei
Background: Recently, transition quadrupole moments in rotational bands of
even-mass neutron-rich isotopes of molybdenum and ruthenium nuclei have been
measured. The new data have provided a challenge for theoretical descriptions
invoking stable triaxial deformations.
Purpose: To understand experimental data on rotational bands in the
neutron-rich Mo-Ru region, we carried out theoretical analysis of moments of
inertia, shapes, and transition quadrupole moments of neutron-rich even-even
nuclei around Ru using self-consistent mean-field and shell model
techniques.
Methods: To describe yrast structures in Mo and Ru isotopes, we use nuclear
Density Functional Theory (DFT) with the optimized energy density functional
UNEDF0. We also apply Triaxial Projected Shell Model (TPSM) to describe yrast
and positive-parity, near-yrast band structures.
Results: Our self-consistent DFT calculations predict triaxial ground-state
deformations in Mo and Ru and reproduce the
observed low-frequency behavior of moments of inertia. As the rotational
frequency increases, a negative- structure, associated with the aligned
pair, becomes energetically favored. The computed transition
quadrupole moments vary with angular momentum, which reflects deformation
changes with rotation; those variations are consistent with experiment. The
TPSM calculations explain the observed band structures assuming stable triaxial
shapes.
Conclusions: The structure of neutron-rich even-even nuclei around Ru
is consistent with triaxial shape deformations. Our DFT and TPSM frameworks
provide a consistent and complementary description of experimental data.Comment: 10 pages, 12 figure
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