14,371 research outputs found
Numerical study on Schramm-Loewner Evolution in nonminimal conformal field theories
The Schramm-Loewner evolution (SLE) is a powerful tool to describe fractal
interfaces in 2D critical statistical systems. Yet the application of SLE is
well established for statistical systems described by quantum field theories
satisfying only conformal invariance, the so called minimal conformal field
theories (CFTs). We consider interfaces in Z(N) spin models at their self-dual
critical point for N=4 and N=5. These lattice models are described in the
continuum limit by non-minimal CFTs where the role of a Z_N symmetry, in
addition to the conformal one, should be taken into account. We provide
numerical results on the fractal dimension of the interfaces which are SLE
candidates for non-minimal CFTs. Our results are in excellent agreement with
some recent theoretical predictions.Comment: 4 pages, 2 figures, v2: typos corrected, published versio
De la Expansion Desarrollista a las Extensiones Aulicas : Un Desafío Para la Gestión del Conocimiento en la Universidad Argentina
En esta ponencia nos proponemos abordar algunas consideraciones sobre la universidad como objeto de estudio en relación a los modos de producción y distribución del conocimiento. Para este propósito revisamos las transformaciones cuanti - cualitativas de la educación superior latinoamericana acaecidas desde mediados de los años 1950, momento en el que las universidades diseñadas para las élites comienzan una apertura hacia sectores sociales medios y bajos. Esta expansión matricular y diversificación institucional configuró lo que hoy conocemos como sistemas universitarios, modificando las condiciones de producción, organización y distribución del conocimiento; cambios que a lo largo de la segunda mitad del siglo XX plantean diferentes y complejos desafíos para la gestión de las universidades. En el caso argentino la universidad pública resultó atravesada por demandas de acceso que fueron canalizadas a través de nuevas creaciones localizadas fuera de los grandes centros urbanos. Esa modalidad visible hasta mediados de los años 1970 hacia fines de los años 1980 comienza a adquirir una nueva dinámica a raíz del corrimiento del estado, la fuerte participación de la iniciativa privada y la generación de criterios de mercado que introducen nuevas reglas en la creación - difusión del conocimiento y sus modos de gestión
Two hydroxy pyridinecarboxylic acid derivatives as a possible chelating agents in neurodegenerative disease; equilibrium complexation studies with Cu(II), Zn(II).
The metal ion chelators 4-hydroxy-5-methyl-3-pyridinecarboxylic acid (DQ5) and 1,5-dimethyl-4-hydroxy-3-pyridinecarboxylic acid (DQ715) and Cu(II) and Zn(II) were investigated with the aim to restore the homeostasis of the brain Cu(II) and Zn(II) in neurodegenerative diseases. The proton dissociation constants of the ligands, the stability constants, and the coordination modes of the metal complexes formed were determined by pH-potentiometric, and spectral (UV–Vis and EPR or 1H NMR) methods. The results show that in slightly acidic and neutral pH range mono and bis complexes are formed through bidentate coordination of the ligands. The biological MTT-test reveals that the DQ715 ligand is able to lower the cytotoxic effect of Cu(II) in human embryonic kidney HEK-293 cells. Our studies revealed, however, that none of the chelators were efficient enough to withdraw these metal ions from the amyloid aggregates
Quantification of habitat fragmentation reveals extinction risk in terrestrial mammals
Although habitat fragmentation is often assumed to be a primary driver of extinction, global patterns of fragmentation and its relationship to extinction risk have not been consistently quantified for any major animal taxon. We developed high-resolution habitat fragmentation models and used phylogenetic comparative methods to quantify the effects of habitat fragmentation on the world's terrestrial mammals, including 4,018 species across 26 taxonomic Orders. Results demonstrate that species with more fragmentation are at greater risk of extinction, even after accounting for the effects of key macroecological predictors, such as body size and geographic range size. Species with higher fragmentation had smaller ranges and a lower proportion of high-suitability habitat within their range, andmost high-suitability habitat occurred outside of protected areas, further elevating extinction risk. Our models provide a quantitative evaluation of extinction risk assessments for species, allow for identification of emerging threats in species not classified as threatened, and provide maps of global hotspots of fragmentation for the world's terrestrial mammals. Quantification of habitat fragmentation will help guide threat assessment and strategic priorities for global mammal conservation
Effects of Animal-Assisted Therapy (AAT) in Alzheimer’s Disease: A Case Study
Alzheimer’s disease (AD) is a neurodegenerative disorder, characterized by cortical dementia
and irreversibly progressive developments leading to a vegetative state and, finally, to death.
Although many aspects of its etiology, diagnosis and treatment still remain obscure and the current approach
to the disease mostly suffers from limited and low-efficiency therapeutic means, nevertheless,
recent interventions have aimed at improving patients’ quality of life through nonpharmacological
approaches, including animal-assisted therapy (AAT), arousing growing interest. In order to assess
the physiological and neuropsychological effects of AAT on AD, 24 residents of a rest house in
northern Italy were enrolled. The intervention consisted of one 45-minute AAT session per week
over ten weeks. Twelve residents (six AD and six non-AD) received AAT and twelve (six AD and
six non-AD) were controls. In order to evaluate the physiological and clinical effect of AAT on AD
residents, three cardiac parameters, including the systolic and diastolic blood pressure and heart
rate, were measured. Moreover, the neurocognitive and depressive states were assessed by the Mini
Mental State Examination and the Geriatric Depression Scale, respectively. Analyses were performed
by a four-way ANOVA model (including two ways for repeated measures) considering each main
effect and interaction possible in the design. Our findings, despite the small sample size, suggest that
AAT has a positive significant effect on physiological parameters and neurocognitive impairment,
while no effect was observed on the depression level
Studio della formazione di complessi tra alluminio e molecole di interesse ambientale, biologico e farmaceutico
In this thesis work, the coordination properties of several ligands with pharmaceutical, biological and toxicological properties towards Al3+ have been studied. The investigated molecules are 3-hydroxy-2-(1H)-pyridinone (HPyr), 2-hydroxyphenylethanone (HPE), 2-hydroxybenzeneacetic acid (HBA), 2-hydroxynicotinic acid (HNic), 3-hydroxypicolinic acid (HPic), and glutamic acid (Glu).
The reliability of the speciation data has been considered as one of the primary goals. For this reason, each metal-ligand system has been studied by means of a combination of more analytical techniques, so that independent results have been obtained regarding the stoichiometry of the existing complexes and their stability constants. The techniques employed have been potentiometry, UV-Vis spectrophotometry, and 1H-NMR spectroscopy. For HPyr it was also possible to obtain a crystal, so that the structure of an Al-HPyr complex has been evaluated by means of a X-ray diffractometric analysis.
The complexation strength of the studied ligands has been compared each other and with the complexation strength of other ligands previously studied in the literature. The comparison results indicate that Al3+ complexes can be very stable only if the chelating oxygens bear a significant partial negative charge and they can form a 5 or 6-membered chelation ring. HBA forms very weak complexes, as a 7-membered chelation ring is formed by this ligand. In the case of Glu, the complexes are weak because the metal centre is coordinated also by nitrogen, which has a lower affinity towards Al3+ than negatively charged oxygens. HPE bears two oxygens and forms a six-membered chelation ring. However, this ligand forms much weaker complexes than HPyr, HNic, and HPic, because the net negative charge on the HPE oxygens is 0.5, and not (practically) –1 as it is in the other three ligands.
Another aim of this work was the set-up of a new computer programme, PITMAP, which can be used for the elaboration of potentiometric titrations. PITMAP input files are the titration data, and the output results are the stability constants of the species which form in solution at equilibrium, through fitting of experimental parameters
Microscopic origin of Heisenberg and non-Heisenberg exchange interactions in ferromagnetic bcc Fe
By means of first principles calculations we investigate the nature of
exchange coupling in ferromagnetic bcc Fe on a microscopic level. Analyzing the
basic electronic structure reveals a drastic difference between the
orbitals of and symmetries. The latter ones define the shape of
the Fermi surface, while the former ones form weakly-interacting impurity
levels. We demonstrate that, as a result of this, in Fe the orbitals
participate in exchange interactions, which are only weakly dependent on the
configuration of the spin moments and thus can be classified as
Heisenberg-like. These couplings are shown to be driven by Fermi surface
nesting. In contrast, for the states the Heisenberg picture breaks down,
since the corresponding contribution to the exchange interactions is shown to
strongly depend on the reference state they are extracted from. Our analysis of
the nearest-neighbour coupling indicates that the interactions among
states are mainly proportional to the corresponding hopping integral and thus
can be attributed to be of double-exchange origin.Comment: 5 pages, 4 figure
Ripening-induced changes in microbial groups of artisanal Sicilian goats' milk cheese.
Changes in the microbial flora of "Caprino dei Nebrodi", a raw goat's milk cheese produced in Sicily, were studied during ripening. From 2 batches of cheese, 4 samples were taken at day 0, 2, 15, and 30 of ripening. Also, samples of curd and milk used in the manufacturing process were analyzed. By the end of the ripening process (day 30), high log10 cfu/g were found for Lactobacilli (7.20), Lattococci (7.10), and Enterococci (7.00), whereas counts of Enterobacteriaceae (3.91), Escherichia coli (3.30), and Staphylococcus (3.89) were found to be lower. The study provides useful information on the microbiological properties of "Caprino dei Nebrodi" cheese, and the results obtained suggest that in order to increase the quality of this artisanal product, it is necessary to improve the sanitary conditions of milking and cheese-making. The study was intended as a preliminary step towards the isolation and identification of bacterial species found in this type of goat's cheese
SOFTWARE FOR WEATHER DATABASES MANAGEMENT AND CONSTRUCTION OF REFERENCE YEARS
The purpose of this paper is to illustrate a procedure that permits, starting from a sufficiently long database of time series, the construction of a Reference Year (RY) of hourly weather data according to the rules of ISO 15927-4 standard. In order to facilitate the management of the weather database and to allow the users to easily generate
the file, an algorithm has been implemented in Microsoft Visual Basic for Application (VBA). By this way, the application of the ISO 15927-4 is possible even using a popular software tool such as Microsoft Excel or Access without any other expensive specialized software. Such tool allows to
fulfil all the procedures mentioned in ISO 15927- 4 giving as result a time series of 8760 values of several weather variables, ready to be used in any software for energy simulation of buildings
HST Grism Observations of a Gravitationally Lensed Redshift 10 Galaxy
We present deep spectroscopic observations of a Lyman-break galaxy candidate
(hereafter MACS1149-JD) at with the Space
Telescope () WFC3/IR grisms. The grism observations were taken at
4 distinct position angles, totaling 34 orbits with the G141 grism, although
only 19 of the orbits are relatively uncontaminated along the trace of
MACS1149-JD. We fit a 3-parameter (, F160W mag, and Ly equivalent
width) Lyman-break galaxy template to the three least contaminated grism
position angles using an MCMC approach. The grism data alone are best fit with
a redshift of ( confidence), in
good agreement with our photometric estimate of
( confidence). Our analysis
rules out Lyman-alpha emission from MACS1149-JD above a equivalent
width of 21 \AA{}, consistent with a highly neutral IGM. We explore a scenario
where the red /IRAC color of the galaxy
previously pointed out in the literature is due to strong rest-frame optical
emission lines from a very young stellar population rather than a 4000 \AA{}
break. We find that while this can provide an explanation for the observed IRAC
color, it requires a lower redshift (), which is less preferred
by the imaging data. The grism data are consistent with both
scenarios, indicating that the red IRAC color can still be explained by a 4000
\AA{} break, characteristic of a relatively evolved stellar population. In this
interpretation, the photometry indicate that a Myr stellar
population is already present in this galaxy only after
the Big Bang.Comment: Accepted to ApJ. This is the accepted versio
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