746 research outputs found
Superconducting Fluctuation Corrections to the Thermal Current in Granular Metals
The first-order superconducting fluctuation corrections to the thermal
conductivity of a granular metal are calculated. A suppression of thermal
conductivity proportional to is observed in a region not too
close to the critical temperature . As , a saturation of the
correction is found, and its sign depends on the ratio between the barrier
transparency and the critical temperature. In both regimes, the Wiedemann-Franz
law is violated.Comment: 9 pages, 7 figures. Replaced with published version. Important
change
Two-spin entanglement distribution near factorized states
We study the two-spin entanglement distribution along the infinite
chain described by the XY model in a transverse field; closed analytical
expressions are derived for the one-tangle and the concurrences ,
being the distance between the two possibly entangled spins, for values of the
Hamiltonian parameters close to those corresponding to factorized ground
states. The total amount of entanglement, the fraction of such entanglement
which is stored in pairwise entanglement, and the way such fraction distributes
along the chain is discussed, with attention focused on the dependence on the
anisotropy of the exchange interaction. Near factorization a characteristic
length-scale naturally emerges in the system, which is specifically related
with entanglement properties and diverges at the critical point of the fully
isotropic model. In general, we find that anisotropy rule a complex behavior of
the entanglement properties, which results in the fact that more isotropic
models, despite being characterized by a larger amount of total entanglement,
present a smaller fraction of pairwise entanglement: the latter, in turn, is
more evenly distributed along the chain, to the extent that, in the fully
isotropic model at the critical field, the concurrences do not depend on .Comment: 14 pages, 6 figures. Final versio
Comparison of two echocardiographic views for evaluating the right pulmonary artery distensibility index in dogs.
Echocardiographic evaluation of the right pulmonary artery distensibility
index (RPAD index) was recently described as a valuable
method for early detection and severity evaluation of
pulmonary arterial hypertension in dogs. RPAD index is calculated
as the percentage change in diameter of the right pulmonary
artery (RPA) between systole and diastole, obtained by M-mode
echocardiography from the right parasternal long axis view. The
aim of this study was to compare the RPAD index obtained by 2
different echocardiographic views in dogs. The study design was a
prospective, multicenter, observational study. Forty-five clientowned
dogs from different breeds were included: 31 dogs with
heart disease and 14 healthy dogs. Two different right parasternal
views, long axis (RPLA) and short axis (RPSA), were used to
measure the RPAD index. From the RPLA view (method 1) and
RPSA view (method 2) a short axis and a long axis image were
respectively optimized for the right pulmonary artery. The RPAD
index was calculated by M-mode as the percentage change in
diameter of the right pulmonary artery: [(systolic diameter - diastolic
diameter)/ systolic diameter]*100. Measurements were done
off-line as an average of 5 consecutive cardiac cycles by a single
investigator blinded to the dogs’ diagnosis. A Pearson and a
Bland-Altman test were used to assess correlation and agreement
between the 2 methods, respectively. Intra- and inter-observer
measurement variability was quantified by average coefficient of
variation (CV). Level of significance was set at P < 0.05. M-mode
evaluation of the RPAD index was satisfactorily obtained by both
methods in all dogs. Pearson test showed a strong positive linear
correlation between the values of RPAD index obtained from both
methods (r2 = 0.9346, P < 0.0001). Bland-Altman test showed a
good agreement between the 2 methods in estimating RPAD index
(bias = 0.51%, SD = 2.96%, 95% limits of agreement = 5.30,
6.33%). The mean difference between the 2 methods was 0.51%
(95% confidence interval = 0.35; 1.35). Intra- and inter-observer
measurement variability was clinically acceptable (CV<10%).The
study showed a good agreement between short axis and long axis
M-mode evaluation of RPA. Both methods can be used interchangeably
to evaluate RPAD index. Further studies are needed
to evaluate the RPAD index in a larger population of healthy dogs
and the diagnostic and prognostic role of this echocardiographic
parameter in dogs with different types of pulmonary hypertension
Syphilis with HIV in Florence, 2003-2009: a 7-year epidemiological study.
SUMMARYThe aims of this study were to describe the trend of acquired syphilis in the city of Florence and its province over a 7-year period, to investigate sexual behaviours in the syphilis-infected population and to analyse syphilis/HIV co-infection. A total of 259 patients were classified according to age, sex and HIV infection. We estimated that from 2004 to 2008 cases increased by 248%. Most patients with concurrent HIV infection were male (31–45 years), but 40- to 60-year-old men who had sex with men predominated in both male and HIV-positive patients. Oral sex was identified as the most significant route of transmission, although most patients did not consider it so. Late-presenters with HIV accounted for 33% of HIV-positive patients: they were unaware of their HIV status and showed syphilis lesions only. In these cases, syphilis heralded the presence of HIV infection and allowed earlier diagnosis
Line-field confocal optical coherence tomography: a new tool for non-invasive differential diagnosis of pustular skin disorders
Background The spectrum of pustular skin disorders (PSD) is large and particularly challenging, including inflammatory, infectious and amicrobial diseases. Moreover, although pustules represent the unifying clinical feature, they can be absent or not fully developed in the early stage of the disease. The line-field confocal optical coherence tomography (LC-OCT) is a recently developed imaging technique able to perform a non-invasive, in vivo, examination of the epidermis and upper dermis, reaching very high image resolution and virtual histology. Objectives We aimed to investigate the potentialities of LC-OCT in the non-invasive differential diagnosis of a series of 11 PSD with different aetiology, microscopic features, body location and incidence rates. Materials and Methods Complete LC-OCT imaging (i.e. 2D/3D frames, videos) was performed on a total of 19 patients (10 females and 9 males) aged between 35 and 79 years. Images were blindly evaluated and compared with corresponding histopathologic findings. Results The LC-OCT imaging was able to detect with high accuracy the pustule structure including shape, margins, morphology and cellular content, along with peculiar epidermal and adnexal alterations in each condition, including: Acute Generalized Exanthematous Pustulosis, Generalized pustular psoriasis, Generalized pustular figurate erythema, Subcorneal Pustular Dermatosis, Intraepidermal IgA pustulosis, Palmoplantar pustulosis, Palmoplantar pustular psoriasis. Herpetic whitlow, Acrodermatitis continua of Hallopeau, Vesicopustular Sweet syndrome and Vesicopustular Eosinophilic cellulitis, with pustular appearance, were also compared. Conclusions The new LC-OCT can represent a rapid, non-invasive and painless tool which can help differentiating among PSD of different aetiology and microscopic morphology in clinical mimickers in daily practice
Bilateral primary renal lymphoma treated by surgery and chemotherapy.
Abstract not available
Quantum fluctuations in one-dimensional arrays of condensates
The effects of quantum and thermal fluctuations upon the fringe structure
predicted to be observable in the momentum distribution of coupled
Bose-Einstein condensates are studied by the effective-potential method. For a
double-well trap, the coherence factor recently introduced by Pitaevskii and
Stringari [Phys. Rev. Lett. 87, 180402 (2001)] is calculated using the
effective potential approach and is found in good agreement with their result.
The calculations are extended to the case of a one-dimensional array of
condensates, showing that quantum effects are essentially described through a
simple renormalization of the energy scale in the classical analytical
expression for the fringe structure. The consequences for the experimental
observability are discussed.Comment: RevTeX, 4 pages, 5 eps figures (published version with updated
references
Sentinel-2 time series analysis for monitoring multi-taxon biodiversity in mountain beech forests
Biodiversity monitoring represents a major challenge to supporting proper forest ecosystem management and biodiversity conservation. The latter is indeed shifting in recent years from single-species to multi-taxon approaches. However, multi-taxonomic studies are quite rare due to the effort required for performing field surveys. In this context, remote sensing is a powerful tool, continuously providing consistent and open access data at a different range of spatial and temporal scales. In particular, the Sentinel-2 (S2) mission has great potential to produce reliable proxies for biological diversity. In beech forests of two Italian National Parks, we sampled the beetle fauna, breeding birds, and epiphytic lichens. First, we calculated Shannon's entropy and Simpson's diversity. Then, to produce variables for biodiversity assessment, we exploited S2 data acquired in the 4 years 2017-2021. S2 images were used to construct spectral bands and photosynthetic indices time series, from which 91 harmonic metrics were derived. For each taxon and multi-taxon community, we assessed the correlation with S2 harmonic metrics, biodiversity indices, and forest structural variables. Then, to assess the potential of the harmonic metrics in predicting species diversity in terms of Shannon's and Simpson's biodiversity indices, we also fit a random forests model between each diversity index and the best 10 harmonic metrics (in terms of absolute correlation, that is, the magnitude of the correlation) for each taxon. The models' performance was evaluated via the relative root mean squared error (RMSE%). Overall, 241 beetle, 27 bird, and 59 lichen species were recorded. The diversity indices were higher for the multi-taxon community than for the single taxa. They were generally higher in the CVDA site than in GSML, except for the bird community. The highest correlation values between S2 data and biodiversity indices were recorded in CVDA for multi-taxon and beetle communities (| r| = 0.52 and 0.38, respectively), and in GSML for lichen and beetle communities (| r| = 0.34 and 0.26, respectively). RMSE% ranged between 2.53 and 9.99, and between 8.1 and 16.8 for the Simpson and Shannon index, respectively. The most important variables are phase and RMSE of red-Edge bands for bird and lichen communities, while RMSE and time of tassel cap and from EVI indices for beetles and multi-taxon diversity. Our results demonstrate that S2 data can be used for identifying potential biodiversity hotspots, showing that the herein presented harmonic metrics are informative for several taxa inhabiting wood, giving concrete support to cost-effective biodiversity monitoring and nature-based forest management in complex mountain systems
Long tree-ring chronologies provide evidence of recent tree growth decrease in a central african tropical forest
It is still unclear whether the exponential rise of atmospheric CO2 concentration has produced a fertilization effect on tropical forests, thus incrementing their growth rate, in the last two centuries. As many factors affect tree growth patterns, short -term studies might be influenced by the confounding effect of several interacting environmental variables on plant growth. Long-term analyses of tree growth can elucidate long-term trends of plant growth response to dominant drivers. The study of annual rings, applied to long tree-ring chronologies in tropical forest trees enables such analysis. Long-term tree-ring chronologies of three widespread African species were measured in Central Africa to analyze the growth of trees over the last two centuries. Growth trends were correlated to changes in global atmospheric CO2 concentration and local variations in the main climatic drivers, temperature and rainfall. Our results provided no evidence for a fertilization effect of CO2 on tree growth. On the contrary, an overall growth decline was observed for all three species in the last century, which appears to be significantly correlated to the increase in local temperature. These findings provide additional support to the global observations of a slowing down of C sequestration in the trunks of forest trees in recent decades. Data indicate that the CO2 increase alone has not been sufficient to obtain a tree growth increase in tropical trees. The effect of other changing environmental factors, like temperature, may have overridden the fertilization effect of CO2
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