2,768 research outputs found
The Utilization of Heat Exchangers for Energy Conservation in Air Conditioning
This paper investigates the characteristics of heat exchanger (HPHE) as an efficient
coolness recovery unit in air conditioning through experimental studies. It was conducted
under a multiple-nozzle code tester based on the ASHRAE standards. The wind tunnel
was subjected to airflow with considerable variation in its inlet air temperature. Among
the factors being investigated are the air velocity, inlet and outlet air temperatures,
overall efficiency and the number of rows in longitudinal direction. The data obtained
were compared with the results predicted by previous theoretical studies. Good agreement
was observed
Geometric Aspects of the Moduli Space of Riemann Surfaces
This is a survey of our recent results on the geometry of moduli spaces and
Teichmuller spaces of Riemann surfaces appeared in math.DG/0403068 and
math.DG/0409220. We introduce new metrics on the moduli and the Teichmuller
spaces of Riemann surfaces with very good properties, study their curvatures
and boundary behaviors in great detail. Based on the careful analysis of these
new metrics, we have a good understanding of the Kahler-Einstein metric from
which we prove that the logarithmic cotangent bundle of the moduli space is
stable. Another corolary is a proof of the equivalences of all of the known
classical complete metrics to the new metrics, in particular Yau's conjectures
in the early 80s on the equivalences of the Kahler-Einstein metric to the
Teichmuller and the Bergman metric.Comment: Survey article of our recent results on the subject. Typoes
corrrecte
The K\"ahler-Ricci flow on surfaces of positive Kodaira dimension
The existence of K\"ahler-Einstein metrics on a compact K\"ahler manifold has
been the subject of intensive study over the last few decades, following Yau's
solution to Calabi's conjecture. The Ricci flow, introduced by Richard Hamilton
has become one of the most powerful tools in geometric analysis.
We study the K\"ahler-Ricci flow on minimal surfaces of Kodaira dimension one
and show that the flow collapses and converges to a unique canonical metric on
its canonical model. Such a canonical is a generalized K\"ahler-Einstein
metric. Combining the results of Cao, Tsuji, Tian and Zhang, we give a metric
classification for K\"aher surfaces with a numerical effective canonical line
bundle by the K\"ahler-Ricci flow. In general, we propose a program of finding
canonical metrics on canonical models of projective varieties of positive
Kodaira dimension
In vitro method to study antifungal perfusion in Candida Biofilms
Antimycotic perfusion through Candida biofilms was demonstrated by a modification of a simple in vitro diffusion cell bioassay system. Using this model, the perfusion of three commonly used antifungal agents, amphotericin B, fluconazole, and flucytosine, was investigated in biofilms of three different Candida species (i.e., Candida albicans, Candida parapsilosis, and Candida krusei) that were developed on microporous filters. Scanning electron microscopy revealed that C. albicans formed a contiguous biofilm with tightly packed blastospores and occasional hyphae compared with C. parapsilosis and C. krusei, which developed confluent biofilms displaying structural heterogeneity and a lesser cell density, after 48 h of incubation on nutrient agar. Minor structural changes were also perceptible on the superficial layers of the biofilm after antifungal perfusion. The transport of antifungals to the distal biofilm-substratum interface was most impeded by C. albicans biofilms in comparison to C. parapsilosis and C. krusei. Fluconazole and flucytosine demonstrated similar levels of perfusion, while amphotericin B was the least penetrant through all three biofilms, although the latter appeared to cause the most structural damage to the superficial cells of the biofilm compared with the other antifungals. These results suggest that the antifungal perfusion through biofilm mode of growth in Candida is dependent both on the antimycotic and the Candida species in question, and in clinical terms, these phenomena could contribute to the failure of Candida biofilm-associated infections. Finally, the in vitro model we have described should serve as a useful system to investigate the complex interactions that appear to operate in vivo within the biofilm-antifungal interphase.published_or_final_versio
Giant planar Hall effect in colossal magnetoresistive La0.84Sr0.16MnO3 thin films
The transverse resistivity in thin films of La0.84Sr0.16MnO3 (LSMO) exhibits sharp field-symmetric jumps below TC . We show that a likely source of this behavior is the giant planar Hall effect combined with biaxial magnetic anisotropy. The effect is comparable in magnitude to that observed recently in the magnetic semiconductor Ga(Mn)As. It can be potentially used in applications such as magnetic sensors and nonvolatile memory devices
Temperature dependent photoluminescence of organic semiconductors with varying backbone conformation
We present photoluminescence studies as a function of temperature from a
series of conjugated polymers and a conjugated molecule with distinctly
different backbone conformations. The organic materials investigated here are:
planar methylated ladder type poly para-phenylene, semi-planar polyfluorene,
and non-planar para hexaphenyl. In the longer-chain polymers the
photoluminescence transition energies blue shift with increasing temperatures.
The conjugated molecules, on the other hand, red shift their transition
energies with increasing temperatures. Empirical models that explain the
temperature dependence of the band gap energies in inorganic semiconductors can
be extended to explain the temperature dependence of the transition energies in
conjugated molecules.Comment: 8 pages, 9 figure
Ternary q-Virasoro-Witt Hom-Nambu-Lie algebras
In this paper we construct ternary -Virasoro-Witt algebras which
-deform the ternary Virasoro-Witt algebras constructed by Curtright, Fairlie
and Zachos using enveloping algebra techniques. The ternary
Virasoro-Witt algebras constructed by Curtright, Fairlie and Zachos depend on a
parameter and are not Nambu-Lie algebras for all but finitely many values of
this parameter. For the parameter values for which the ternary Virasoro-Witt
algebras are Nambu-Lie, the corresponding ternary -Virasoro-Witt algebras
constructed in this article are also Hom-Nambu-Lie because they are obtained
from the ternary Nambu-Lie algebras using the composition method. For other
parameter values this composition method does not yield Hom-Nambu Lie algebra
structure for -Virasoro-Witt algebras. We show however, using a different
construction, that the ternary Virasoro-Witt algebras of Curtright, Fairlie and
Zachos, as well as the general ternary -Virasoro-Witt algebras we construct,
carry a structure of ternary Hom-Nambu-Lie algebra for all values of the
involved parameters
Implementing an eleven year through-train model to complete Primary and Secondary Education: creating a platform for accommodating the newest pedagogical practices and technologies in school
In educational transformation, Logos Academy of Hong Kong has started to create space in two aspects: to accommodate for new learning areas, and to use the most updated technologies for learning.
In different Learning Stages, new learning areas like "Family Life Education", "Analytical study of Current Issues", Mind-mapping, MegaSkills and Media Education are introduced. The teachers will design different level- and age-appropriate activities and assignments that encourage the mastery of basic concepts and development of aesthetic appreciation, family life education, character formation, physique building and inquiry/research skills. Moreover, integrated tasks and projects intertwining with different study skills are mounted to enable the children to experiment creative designs and try out increasingly complex investigations.
To facilitate learning and teaching, Logos Academy also creates new platforms to use the newest technologies for pre-lesson use, for lesson use, and for post-lesson use. It is reviewed that with the aid of some updated technologies, our teachers are committed to facilitate change, reflect on current practices, explore further improvements in new learning areas and to use the new technologies effectively - which will in turn enhance the effectiveness of integrated study skills, self-directed learning, team work and social interaction of the students
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