744 research outputs found
Ising transition in the two-dimensional quantum Heisenberg model
We study the thermodynamics of the spin- two-dimensional quantum
Heisenberg antiferromagnet on the square lattice with nearest () and
next-nearest () neighbor couplings in its collinear phase (),
using the pure-quantum self-consistent harmonic approximation. Our results show
the persistence of a finite-temperature Ising phase transition for every value
of the spin, provided that the ratio is greater than a critical value
corresponding to the onset of collinear long-range order at zero temperature.
We also calculate the spin- and temperature-dependence of the collinear
susceptibility and correlation length, and we discuss our results in light of
the experiments on LiVOSiO and related compounds.Comment: 4 page, 4 figure
Weak localization effects in granular metals
The weak localization correction to the conductivity of a granular metal is
calculated using the diagrammatic technique in the reciprocal grain lattice
representation. The properties of this correction are very similar to that one
in disordered metal, with the replacement of the electron mean free path by the grain diameter and the dimensionless conductance by the
tunnelling dimensionless conductance . In particular, we demonstrate
that at zero temperature no conducting phase can exist for dimensions . We also analyze the WL correction to magnetoconductivity in the weak field
limit.Comment: 4 pages, 3 figures; minor corrections adde
Reentrant behavior of the phase stiffness in Josephson junction arrays
The phase diagram of a 2D Josephson junction array with large substrate
resistance, described by a quantum XY model, is studied by means of Fourier
path-integral Monte Carlo. A genuine Berezinskii-Kosterlitz-Thouless transition
is found up to a threshold value g* of the quantum coupling, beyond which no
phase coherence is established. Slightly below g* the phase stiffness shows a
reentrant behavior with temperature, in connection with a low-temperature
disappearance of the superconducting phase, driven by strong nonlinear quantum
fluctuations.Comment: 4 pages, 7 figures, to appear in Phys.Rev.Let
An Activity Classifier based on Heart Rate and Accelerometer Data Fusion
The European project ProeTEX realized a novel set of prototypes based on smart garments
that integrate sensors for the real-time monitoring of physiological, activity-related and environmental
parameters of the emergency operators during their interventions. The availability of these parameters
and the emergency scenario suggest the implementation of novel classification methods aimed at
detecting dangerous status of the rescuer automatically, and based not only on the classical activityrelated
signals, rather on a combination of these data with the physiological status of the subject. Here
we propose a heart rate and accelerometer data fusion algorithm for the activity classification of
rescuers in the emergency context
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
Image Gallery: Super‐high magnification dermoscopy can identify pigmented cells: correlation with reflectance confocal microscopy
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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
An Updated Algorithm Integrated With Patient Data for the Differentiation of Atypical Nevi From Early Melanomas: the idScore 2021
Introduction: It is well known that multiple patient-related risk factors contribute to the development of cutaneous melanoma, including demographic, phenotypic and anamnestic factors. Objectives: We aimed to investigate which MM risk factors were relevant to be incorporated in a risk scoring-classifier based clinico-dermoscopic algorithm. Methods: This retrospective study was performed on a monocentric dataset of 374 atypical melanocytic skin lesions sharing equivocal dermoscopic features, excised in the suspicion of malignancy. Dermoscopic standardized images of 258 atypical nevi (aN) and 116 early melanomas (eMM) were collected along with objective lesional data (i.e., maximum diameter, specific body site and body area) and 7 dermoscopic data. All cases were combined with a series of 10 MM risk factors, including demographic (2), phenotypic (5) and anamnestic (3) ones. Results: The proposed iDScore 2021 algorithm is composed by 9 variables (age, skin phototype I/II, personal/familiar history of MM, maximum diameter, location on the lower extremities (thighs/legs/ ankles/back of the feet) and 4 dermoscopic features (irregular dots and globules, irregular streaks, blue gray peppering, blue white veil). The algorithm assigned to each lesion a score from 0 to 18, reached an area under the ROC curve of 92% and, with a score threshold ≥ 6, a sensitivity (SE) of 98.2% and a specificity (SP) of 50.4%, surpassing the experts in SE (+13%) and SP (+9%).Conclusions: An integrated checklist combining multiple anamnestic data with selected relevant dermoscopic features can be useful in the differential diagnosis and management of eMM and aN exhibiting with equivocal features
UVA-1 phototherapy as adjuvant treatment for eosinophilic fasciitis: in vitro and in vivo functional characterization
Introduction: Eosinophilic fasciitis (EF) is a rare autoimmune disease causing progressive induration of dermal, hypodermal, and muscularis fascia. The exact pathogenesis is yet to be fully understood, and a validated therapy protocol still lacks. We here aimed to realize a clinical–functional characterization of these patients. Materials and methods: A total of eight patients (five males, 45 years average) were treated with adjuvant high-dose UVA-1 phototherapy (90 J/cm), after having received the standard systemic immunosuppressive protocol (oral methylprednisolone switched to methotrexate). Body lesion mapping, Localized Scleroderma Assessment Tool (LoSCAT), Dermatology Life Quality Index (DLQI), High-Resolution Ultrasound (HRUS) (13-17MHz), and ultra HRUS (55–70 MHz) were performed at each examination time taking specific anatomical points. Gene expression analysis at a molecular level and in vitro UVA-1 irradiation was realized on lesional fibroblasts primary cultures. Results: The LoSCAT and the DLQI showed to decrease significantly starting from the last UVA-1 session. A significant reduction in muscularis fascia thickness (−50% on average) was estimated starting from 3 months after the last UVA-1 session and maintained up to 12 months follow-up. Tissues was detected by HRUS. The UVA-1 in vitro irradiation of lesional skin sites cells appeared not to affect their viability. Molecular genes analysis revealed a significant reduction of IL-1ß and of TGF-ß genes after phototherapy, while MMPs 1,2,9 gene expression was enhanced. Comment: These preliminary in vivo and in vitro findings suggest that UVA-1 phototherapy is a safe and useful adjuvant therapy able to elicit anti-inflammatory effects and stimulate tissue matrix digestion and remodeling at lesional sites
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
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