Dynamical Properties of a Haldane Gap Antiferromagnet

We study the dynamic spin correlation function of a spin one antiferromagnetic chain with easy-plane single-ion anisotropy. We use exact diagonalization by the Lancz\H os method for chains of lengths up to N=16 spins. We show that a single-mode approximation is an excellent description of the dynamical properties. A variational calculation allows us to clarify the nature of the excitations. The existence of a two-particle continuum near zero wavevector is clearly seen both in finite-size effects and in the dynamical structure factor. The recent neutron scattering experiments on the quasi-one-dimensional antiferromagnet NENP are fully explained by our results.Comment: 14 pages, SphT/92-135 plain tex with Postscript figures included. Postscipt file available by anonymous ftp at amoco.saclay.cea.fr by get pubs.spht/92-135.ps local_file (290 kb) or get pubs.spht/92-135.ps.Z local_file.Z (compressed - 120 kb

Precise nondivergent analytic formulas for the radiative corrections to the beta energy spectrum in hyperon semileptonic decays over the entire Dalitz plot

Very accurate analytical expressions for the radiative corrections of unpolarized hyperons semileptonic decays of charged and neutral baryons have been obtained in the recent past. Some of these formulas contain logarithmic singularities at the edges of the Dalitz plot for the three- and four-body decays. These singularities are analyzed and integrated analytically to obtain new divergentless formulas for the energy spectrum of the produced beta particle. The new equations contain terms of the order alpha times the momentum transfer, are applicable to any beta decay process and are suitable for a model-independent experimental analysis.Comment: 22 pages, 4 figure

From model-driven software development processes to problem diagnoses at runtime

Following the “convention over configuration” paradigm, model-driven software development (MDSD) generates code to implement the “default” behaviour that has been specified by a template separate from the input model. On the one hand, developers can produce end-products without a full understanding of the templates; on the other hand, the tacit knowledge in the templates is subtle to diagnose when a runtime software failure occurs. Therefore, there is a gap between templates and runtime adapted models. Generalising from the concrete problematic examples in MDSD processes to a model-based problem diagnosis, the chapter presents a procedure to separate the automated fixes from those runtime gaps that require human judgments

Examining theories of cognitive ageing using the false memory paradigm

Changes in memory performance with advancing age have been well-documented, even in the absence of brain injury or dementia. The mechanisms underlying cognitive ageing are still a matter of debate. The current paper describes a comparison between young (18-25 year old) and older (60+ years) adults using the Deese-Roediger-McDermott false memory paradigm and manipulating the number of words included in the memory lists. Two key theories of cognitive ageing (the Inhibitory Deficit Hypothesis and the Transmission Deficit Hypothesis) predict opposing patterns on this task. Results showed that longer lists increase the likelihood that a lure is retrieved and that older adults are more susceptible to false memories than are younger adults. We argue that these findings are supportive of the Inhibitory Deficit Hypothesis and cannot easily be reconciled with the Transmission Deficit Hypothesis account

Bridging the Gap: Capturing the Lyα\alpha Counterpart of a Type-II Spicule and its Heating Evolution with VAULT2.0 and IRIS Observations

We present results from an observing campaign in support of the VAULT2.0 sounding rocket launch on September 30, 2014. VAULT2.0 is a Ly$\alpha$ (1216 \AA) spectroheliograph capable of providing spectroheliograms at high cadence. Ly$\alpha$ observations are highly complementary to the IRIS observations of the upper chromosphere and the low transition region (TR) but have previously been unavailable. The VAULT2.0 data provide new constraints on upper-chromospheric conditions for numerical models. The observing campaign was closely coordinated with the IRIS mission. Taking advantage of this simultaneous multi-wavelength coverage of target AR 12172 and by using state-of-the-art radiative-MHD simulations of spicules, we investigate in detail a type-II spicule associated with a fast (300 km s$^{-1}$) network jet recorded in the campaign observations. Our analysis suggests that spicular material exists suspended high in the atmosphere but in lower temperatures (seen in Ly$\alpha$) until it is heated and becomes visible in TR temperatures as a network jet. The heating begins lower in the spicule and propagates upwards as a rapidly propagating thermal front. The front is then observed as fast, plane-of-the-sky motion typical of a network jet, but contained inside the pre-existing spicule. This work supports that the high speeds reported in network jets should not be taken as real mass upflows but only as apparent speeds of a rapidly propagating heating front along the pre-existing spicule.Comment: 15 pages, 5 figures and one online movie. Accepted for publication in the Astrophysical Journa

Urban context and climate change impact on the thermal performance and ventilation of residential buildings: a case-study in Athens

Joint conference with the 11th TightVent Conference and the 9th Venticool ConferenceUrban settings and climate change both impact energy use, thermal comfort and ventilation of buildings. This is more noticeable in hot urban areas where the urban heat island effect is more pronounced; also, in densely built urban areas where thermal comfort in naturally ventilated buildings is affected by changes in natural ventilation rates because of surrounding obstructions. In some cases, overshadowing might alleviate the impact. This paper presents a study of changes in energy demand in residential buildings considering the overlapping effect of climate change and urban heat island intensity in Athens representing a hot European climate and a dense urban setting. The case study building is a real residential building in an urban canyon in central Athens with data obtained from the PRELUDE H2020 project. The impact of urban parameters on air temperature wind speed and solar overshadowing was considered. Urban air temperature was calculated by using the Urban Weather Generator which includes a number of indices such as site coverage, façade to site ratio and average building height; it also considers the building construction materials as well as anthropogenic heat emissions by the operation of the buildings. Urban wind speed was modified using the URBVENT urban canyon model for the computation of wind speed; this model was validated by its proposers in 2005 by measurements in Athens. Solar overshadowing was calculated for the case-study building considering the surrounding buildings. Current-urban and future-urban weather files were generated, and simulations were run considering energy demand and indoor thermal comfort. The thermal simulation results show that in the hot European climate of Athens with densely built urban areas and for a building within an urban canyon, current weather files which include overshadowing, urban heat island and canyon wind will increase the cooling demand by 24% in comparison to using a typical current weather file. However total energy demand (heating and cooling) increased only 3% for lower floors and 12% for higher floors due to the reduction of heating demand. Simulations using future weather files indicated a 66% increase of cooling demand in comparison to using a typical weather file. Future total energy demand increased by 32% for higher floors and 13% for lower floors. If the building is free floating an adaptive thermal comfort analysis indicated that only 25% of the summertime will be comfortable in comparison to the 50% prediction by the current typical weather file. Therefore, the use a suitable weather file to include urban external conditions in thermal simulations is essential for more accurate predictions of energy demand and internal avoidance of overheating in free-floating buildings.European Union’s Horizon 2020 research and innovation programme under Grant Agreement N° 958345 for the PRELUDE project (https://preludeproject.eu)

Modification of Synthesis Process of Lawang\u27s Bark (Cinnamomum Cullilawan Blume) as a Cancer Drug Precursor

Piperonal as a precursor of cancer drug (Curcumin analogues) can be synthesized from extract of lawang\u27s bark (Cinnamomum culilawan Blume) with multiple stages, among others: isolation of essential oils, isolation safrole, safrole isomerization, and synthesis of piperonal. Essential oils were isolated from the bark of lawang (the water content of 46.2%) using a water distillation system with 1/3 volume of high boiler for five hours. Isolation of safrole from lawang bark oils was performed using NaOH solution and purified using reduced pressure distillation system at a temperature of 90-123°C / 1 mmHg. The safrole isomerization was undergone using alkali catalyst (KOH) without solvent at a temperature of 120°C for 8 hours. Oxidation of isosafrol was performed using KMnO4 in acidic conditions using a KTF tween 80 at a temperature below 30°C, and purified using silica gel. Results of isolation yield 0.94% with 14 components were determined through GC-MS, including 67.35% eugenol, safrole 13.96%, 12.61% methyl eugenol, 4-terpineol sineol 1.79% and 1.55%. The isolated safrole yield of 17.21% with purity testing and identification using FTIR, 1H- NMR and GCMS confirmed the product was safrole. The isomerization obtained yield of 77.56% with GC analysis indicated compounds of cis-isosafrole and trans-isosafrole. The results of oxidation obtained yield of 65.63% with a purity of 100% by GCMS and the 1H-NMR indicated the product is piperonal