882 research outputs found
Preparation and Characterization of Monolayers and Multilayers of Preformed Polymers
In an attempt to study which factors determine the transferability of monolayers of preformed polymers from the air-water interface onto substrates we investigated flexible polymers (poly(octadecylmethacrylates) (PODMAs)) and α-helical polymers (polyglutamates). Pressure-area isotherms show the formation of a liquid-analogous state which depends on temperature and side chain "impurity". Y-mode Langmuir-Blodgett multilayers of these polymers can be formed with a constant transfer ratio under conditions at which a more or less liquid-analogous state exists. Polarized IR spectra suggest that the polyglutamate α helices in the multilayer are oriented with the main axis parallel to the transfer direction and that carbon side chains are practically randomly oriented around the α-helical cylinder. In PODMA multilayers the side chains are perpendicular to the film. In both cases the side chains seem to interdigitate
Towards economic sustainability through adaptable buildings
The existing building stock in most countries does not meet the parameters of economic, social and environmental sustainability. Physical, functional, technological, economical, social and legal obsolescence
are the principal factors driving the decommissioning, refurbishment, alteration and/or adaptation of a
building. In the UK the Government promotes optimum use of the existing building stock through mixed use
in urban centers and encourages conversion of redundant office and retail space into leisure, service and/or
residential uses rather than demolition and renewal. There is therefore a growing need to design new
buildings that are adaptable and flexible over their life span whilst at the same time improving user
satisfaction. A constraint to the implementation of a policy of life span adaptability is the difficulty of
understanding the economic considerations over long time scales. This paper investigates the issues
surrounding the economics of the life span of adaptable buildings, and establishes a conceptual framework
for their economic sustainability.
The investigation is based on a case study of how the uses and function of the built environment and its
supporting infrastructure have changed over a period of 100 years undertaken within a semi-rural Borough in
England, UK. This case study includes a trend analysis identifying the life spans (of buildings), the evolving
planning policies and associated social and cultural issues. A conceptual framework is developed and the
economic impacts of the changes are evaluated through Whole Life Analysis. The validity and reliability of
proposed framework is yet to be tested
Results for the response function determination of the Compact Neutron Spectrometer
The Compact Neutron Spectrometer (CNS) is a Joint European Torus (JET)
Enhancement Project, designed for fusion diagnostics in different plasma
scenarios. The CNS is based on a liquid scintillator (BC501A) which allows good
discrimination between neutron and gamma radiation. Neutron spectrometry with a
BC501A spectrometer requires the use of a reliable, fully characterized
detector. The determination of the response matrix was carried out at the Ion
Accelerator Facility (PIAF) of the Physikalisch-Technische Bundesanstalt (PTB).
This facility provides several monoenergetic beams (2.5, 8, 10, 12 and 14 MeV)
and a 'white field'(Emax ~17 MeV), which allows for a full characterization of
the spectrometer in the region of interest (from ~1.5 MeV to ~17 MeV. The
energy of the incoming neutrons was determined by the time of flight method
(TOF), with time resolution in the order of 1 ns. To check the response matrix,
the measured pulse height spectra were unfolded with the code MAXED and the
resulting energy distributions were compared with those obtained from TOF. The
CNS project required modification of the PTB BC501A spectrometer design, to
replace an analog data acquisition system (NIM modules) with a digital system
developed by the 'Ente per le Nuove tecnologie, l'Energia e l'Ambiente' (ENEA).
Results for the new digital system were evaluated using new software developed
specifically for this project.Comment: Proceedings of FNDA 201
Anharmonicities of giant dipole excitations
The role of anharmonic effects on the excitation of the double giant dipole
resonance is investigated in a simple macroscopic model.Perturbation theory is
used to find energies and wave functions of the anharmonic ascillator.The cross
sections for the electromagnetic excitation of the one- and two-phonon giant
dipole resonances in energetic heavy-ion collisions are then evaluated through
a semiclassical coupled-channel calculation.It is argued that the variations of
the strength of the anharmonic potential should be combined with appropriate
changes in the oscillator frequency,in order to keep the giant dipole resonance
energy consistent with the experimental value.When this is taken into
account,the effects of anharmonicities on the double giant dipole resonance
excitation probabilities are small and cannot account for the well-known
discrepancy between theory and experiment
The cultivation of adaptability in Japan
This paper explores the adaptability of buildings in Japan from the perspective of three distinct practice typologies: large general contractors, large architectural design firms, and small design ateliers. The paper illustrates the cultivation of adaptability in Japan revealing a maturing of concepts into current innovations, trends, priorities, and obstacles in relation to adaptability in design. The paper contextualizes the situation by reviewing the evolution of residential development in support of building adaptability, and the ways in which these policies and concepts have shaped practice and transcended residential design. This evolution is then explored through non-residential case studies undertaken by the three practice types, and supported through a review of critical themes emerging from the interviews. The importance of particular physical characteristics are examined including storey height, location of services, planning modules and structural spacing/spans. The interviews expose the critical relationship between adaptability and different social variables - the state of the market, the role of planning regulations and other legal frameworks; as well as, the misconceptions and variations in the perceptions on the role and meaning adaptability has in practice. The paper is concluded by revealing the lessons learnt, including the unfolding of dependencies outside the ‘black box’ of adaptability (e.g. practice culture, material and, stakeholder mindsets) and the requirement of effective communication of concepts to allow an informed conversation between professionals and with clients and users. Like many other philosophical design concepts in complex processes, adaptability benefits from a mutual understanding, good relationships, communication, integration, and shared goals amongst team members
Anharmonic collective excitation in a solvable model
We apply the time-dependent variational principle, the nuclear field theory,
and the boson expansion method to the Lipkin model to discuss anharmonicities
of collective vibrational excitations. It is shown that all of these approaches
lead to the same anharmonicity to leading order in the number of particles.
Comparison with the exact solution of the Lipkin model shows that these
theories reproduce it quite well.Comment: RevTex, 18 pages, 4 postscript figure
Molecular Phylogenies indicate a Paleo-Tibetan Origin of Himalayan Lazy Toads (Scutiger)
The Himalaya presents an outstanding geologically active orogen and biodiversity hotspot. However, our understanding of the historical biogeography of its fauna is far from comprehensive. Many taxa are commonly assumed to have originated from China-Indochina and dispersed westward along the Himalayan chain. Alternatively, the "Tibetan-origin hypothesis" suggests primary diversification of lineages in Paleo-Tibet, and secondary diversification along the slopes of the later uplifted Greater Himalaya. We test these hypotheses in high-mountain megophryid anurans (Scutiger). Extensive sampling from High Asia, and analyses of mitochondrial (2839\u2009bp) and nuclear DNA (2208\u2009bp), using Bayesian and Maximum likelihood phylogenetics, suggest that the Himalayan species form a distinct clade, possibly older than those from the eastern Himalaya-Tibet orogen. While immigration from China-Indochina cannot be excluded, our data may indicate that Himalayan Scutiger originated to the north of the Himalaya by colonization from Paleo-Tibet and then date back to the Oligocene. High intraspecific diversity of Scutiger implies limited migration across mountains and drainages along the Himalaya. While our study strengthens support for a "Tibetan-origin hypothesis", current sampling (10/22 species; 1 revalidated\ufeff: S. occidentalis) remains insufficient to draw final conclusions on Scutiger but urges comparative phylogeographers to test alternative, geologically supported hypotheses for a true future understanding of Himalayan biogeography
Critical scaling of the a.c. conductivity for a superconductor above Tc
We consider the effects of critical superconducting fluctuations on the
scaling of the linear a.c. conductivity, \sigma(\omega), of a bulk
superconductor slightly above Tc in zero applied magnetic field. The dynamic
renormalization- group method is applied to the relaxational time-dependent
Ginzburg-Landau model of superconductivity, with \sigma(\omega) calculated via
the Kubo formula to O(\epsilon^{2}) in the \epsilon = 4 - d expansion. The
critical dynamics are governed by the relaxational XY-model
renormalization-group fixed point. The scaling hypothesis \sigma(\omega) \sim
\xi^{2-d+z} S(\omega \xi^{z}) proposed by Fisher, Fisher and Huse is explicitly
verified, with the dynamic exponent z \approx 2.015, the value expected for the
d=3 relaxational XY-model. The universal scaling function S(y) is computed and
shown to deviate only slightly from its Gaussian form, calculated earlier. The
present theory is compared with experimental measurements of the a.c.
conductivity of YBCO near Tc, and the implications of this theory for such
experiments is discussed.Comment: 16 pages, submitted to Phys. Rev.
In-medium relativistic kinetic theory and nucleon-meson systems
Within the model of coupled nucleon-meson systems, a
generalized relativistic Lenard--Balescu--equation is presented resulting from
a relativistic random phase approximation (RRPA). This provides a systematic
derivation of relativistic transport equations in the frame of nonequilibrium
Green's function technique including medium effects as well as flucuation
effects. It contains all possible processes due to one meson exchange and
special attention is kept to the off--shell character of the particles. As a
new feature of many particle effects, processes are possible which can be
interpreted as particle creation and annihilation due to in-medium one meson
exchange. In-medium cross sections are obtained from the generalized derivation
of collision integrals, which possess complete crossing symmetries.Comment: See nucl-th/9310032 for revised version which the authors
incompetently resubmitted rather than correctly replacing thi
Mesons and baryons in a soft-wall holographic approach
We discuss a holographic soft-wall model developed for the description of
mesons and baryons with adjustable quantum numbers n, J, L, S. This approach is
based on an action which describes hadrons with broken conformal invariance and
which incorporates confinement through the presence of a background dilaton
field.Comment: 6 pages, Presented by Valery E. Lyubovitskij at LIGHTCONE 2011, 23 -
27 May, 2011, Dalla
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