Ballistic thermophoresis of adsorbates on free-standing graphene

The textbook thermophoretic force which acts on a body in a fluid is proportional to the local temperature gradient. The same is expected to hold for the macroscopic drift behavior of a diffusive cluster or molecule physisorbed on a solid surface. The question we explore here is whether that is still valid on a 2D membrane such as graphene at short sheet length. By means of a non-equilibrium molecular dynamics study of a test system -- a gold nanocluster adsorbed on free-standing graphene clamped between two temperatures $\Delta T$ apart -- we find a phoretic force which for submicron sheet lengths is parallel to, but basically independent of, the local gradient magnitude. This identifies a thermophoretic regime that is ballistic rather than diffusive, persisting up to and beyond a hundred nanometer sheet length. Analysis shows that the phoretic force is due to the flexural phonons, whose flow is known to be ballistic and distance-independent up to relatively long mean-free paths. Yet, ordinary harmonic phonons should only carry crystal momentum and, while impinging on the cluster, should not be able to impress real momentum. We show that graphene, and other membrane-like monolayers, support a specific anharmonic connection between the flexural corrugation and longitudinal phonons whose fast escape leaves behind a 2D-projected mass density increase endowing the flexural phonons, as they move with their group velocity, with real momentum, part of which is transmitted to the adsorbate through scattering. The resulting distance-independent ballistic thermophoretic force is not unlikely to possess practical applications

Multi-species mean-field spin-glasses. Rigorous results

We study a multi-species spin glass system where the density of each species is kept fixed at increasing volumes. The model reduces to the Sherrington-Kirkpatrick one for the single species case. The existence of the thermodynamic limit is proved for all densities values under a convexity condition on the interaction. The thermodynamic properties of the model are investigated and the annealed, the replica symmetric and the replica symmetry breaking bounds are proved using Guerra's scheme. The annealed approximation is proved to be exact under a high temperature condition. We show that the replica symmetric solution has negative entropy at low temperatures. We study the properties of a suitably defined replica symmetry breaking solution and we optimise it within a ziggurat ansatz. The generalized order parameter is described by a Parisi-like partial differential equation.Comment: 17 pages, to appear in Annales Henri Poincar\`

Interpolating the Sherrington-Kirkpatrick replica trick

The interpolation techniques have become, in the past decades, a powerful approach to lighten several properties of spin glasses within a simple mathematical framework. Intrinsically, for their construction, these schemes were naturally implemented into the cavity field technique, or its variants as the stochastic stability or the random overlap structures. However the first and most famous approach to mean field statistical mechanics with quenched disorder is the replica trick. Among the models where these methods have been used (namely, dealing with frustration and complexity), probably the best known is the Sherrington-Kirkpatrick spin glass: In this paper we are pleased to apply the interpolation scheme to the replica trick framework and test it directly to the cited paradigmatic model: interestingly this allows to obtain easily the replica-symmetric control and, synergically with the broken replica bounds, a description of the full RSB scenario, both coupled with several minor theorems. Furthermore, by treating the amount of replicas $n\in(0,1]$ as an interpolating parameter (far from its original interpretation) this can be though of as a quenching temperature close to the one introduce in off-equilibrium approaches and, within this viewpoint, the proof of the attended commutativity of the zero replica and the infinite volume limits can be obtained.Comment: This article is dedicated to David Sherrington on the occasion of his seventieth birthda

Definition of an automated Content-Based Image Retrieval (CBIR) system for the comparison of dermoscopic images of pigmented skin lesions

<p>Abstract</p> <p>Background</p> <p>New generations of image-based diagnostic machines are based on digital technologies for data acquisition; consequently, the diffusion of digital archiving systems for diagnostic exams preservation and cataloguing is rapidly increasing. To overcome the limits of current state of art text-based access methods, we have developed a novel content-based search engine for dermoscopic images to support clinical decision making.</p> <p>Methods</p> <p>To this end, we have enrolled, from 2004 to 2008, 3415 caucasian patients and collected 24804 dermoscopic images corresponding to 20491 pigmented lesions with known pathology. The images were acquired with a well defined dermoscopy system and stored to disk in 24-bit per pixel TIFF format using interactive software developed in C++, in order to create a digital archive.</p> <p>Results</p> <p>The analysis system of the images consists in the extraction of the low-level representative features which permits the retrieval of similar images in terms of colour and texture from the archive, by using a hierarchical multi-scale computation of the Bhattacharyya distance of all the database images representation with respect to the representation of user submitted (query).</p> <p>Conclusion</p> <p>The system is able to locate, retrieve and display dermoscopic images similar in appearance to one that is given as a query, using a set of primitive features not related to any specific diagnostic method able to visually characterize the image. Similar search engine could find possible usage in all sectors of diagnostic imaging, or digital signals, which could be supported by the information available in medical archives.</p

Evaluation of algorithms for photon depth of interaction estimation for the TRIMAGE PET component

The TRIMAGE consortium aims to develop a multimodal PET/MR/EEG brain scanner dedicated to the early diagnosis of schizophrenia and other mental health disorders. The PET component features a full ring made of 18 detectors, each one consisting of twelve 8x8 Silicon PhotoMultipliers (SiPMs) tiles coupled to two segmented LYSO crystal matrices with staggered layers. In each module, the crystals belonging to the bottom layer are coupled one to one to the SiPMs, while each crystal of the top layer is coupled to four crystals of the bottom layer. This configuration allows to increase the crystal thickness while reducing the depth of interaction uncertainty, as photons interacting in different layers are expected to produce different light patterns on the SiPMs. The PET scanner will implement the pixel/layer identification on a front-end FPGA. This will allow increasing the effective bandwidth, setting at the same time restrictions on the complexity of the algorithms to be implemented. In this work two algorithms whose implementation is feasible directly on an FPGA are presented and evaluated. The first algorithm implements a method based on adaptive thresholding, while the other uses a linear Support Vector Machine (SVM) trained to distinguish the light pattern coming from two different layers. The validation of the algorithm performance is carried out by using simulated data generated with the GAMOS Monte Carlo. The obtained results show that the achieved accuracy in layer and pixel identification is above the 90% for both the proposed approaches

Assessment of Exercise Stroke Volume and Its Prediction From Oxygen Pulse in Paralympic Athletes With Locomotor Impairments: Cardiac Long-Term Adaptations Are Possible

The determinants of cardiac output (CO) during exercise, i.e., stroke volume (SV) and heart rate (HR), could differ in Paralympic athletes (PAthl) with spinal cord injury (SCI) with respect to PAthl with locomotor impairments caused by different health conditions (HCs). The purposes of the present study were the comparisons of two groups of PAthl, one with SCI and the other with either amputation (AMP) or post poliomyelitis syndrome (PM), assessing the (1) peak cardiorespiratory responses and determinants (SV and HR) of CO during maximal and submaximal arm cranking exercise (ACE), respectively; (2) correlations between peak oxygen uptake (VO2peak) and the highest SV obtained during submaximal exercise; and (3) correlations between oxygen pulse (O-2 pulse, ratio between VO2 and HR) and both SV and O-2 arterio-venous difference [(a-v)O(2)diff]. Each athlete (19 PAthl with SCI, 9 with AMP, and 5 with PM) completed a continuous incremental cardiopulmonary ACE test to volitional fatigue to assess peak responses. In a different session, CO was indirectly measured through carbon dioxide (CO2) rebreathing method at sub-maximal exercise intensities approximating 30, 50, and 70% of the VO2peak. There were no significant differences between the PAthl groups in age, anthropometry, and VO2peak. However, peak HR was significantly lower, and peak O-2 pulse was significantly higher in PAthl with AMP/PM compared to those with SCI. During sub-maximal exercise, PAthl with AMP/PM displayed significantly higher SV values (154.8 +/- 17.60 ml) than PAthl with SCI (117.1 +/- 24.66 ml). SV correlated significantly with VO2peak in both PAthl with SCI (R-2 = 0.796) and AMP/PM (R-2 = 0.824). O-2 pulse correlated significantly with SV in both PAthl with SCI (R-2 = 0.888) and AMP/PM (R-2 = 0.932) and in the overall sample (R-2 = 0.896). No significant correlations were observed between O-2 pulse and (a-v)O(2)diff. It was concluded that in PAthl with different HCs: (1) significant differences, as a consequence of the different HC, exist in the determinants of CO at maximal and submaximal ACE; (2) SV is a significant determinant of VO2peak, suggesting cardiac adaptations possible also in PAthl with SCI; and (3) SV can be predicted from O-2 pulse measurements during submaximal exercise in both groups of PAthl

Linee guida per lo sviluppo di modelli numerici di flusso in acquiferi porosi: Una proposta IRSA-ISPRA

A livello nazionale, nell'ambito dei procedimenti di bonifica dei siti contaminati, disciplinati dalla parte Quarta – Titolo V del decreto legislativo 152 del 2006, l'implementazione di modelli matematici di flusso e di trasporto dei contaminanti è uno strumento che ha acquisito con il tempo sempre maggiore importanza, soprattutto ai fini della definizione e progettazione degli interventi di messa in sicurezza e bonifica delle acque di falda. Modelli matematici sono utilizzati anche a scala di bacino o sottobacino per la caratterizzazione e la gestione delle risorse idriche sotterranee [...]

Iron and Sulfate influence in methanogenesis route in anaerobic digestion of acetominophen

O paracetamol (acetaminofeno) é um fármaco utilizado no tratamento de várias doenças. Este composto pode ser encontrado no meio ambiente devido ao descarte de medicamentos viáveis ou vencidos no esgoto doméstico. Para não contaminar os corpos hídricos, sistemas biológicos têm sido analisados e utilizados como sistemas de tratamento de esgoto contendo diferentes tipos de compostos químicos, incluindo os provenientes de medicamentos. O estudo analisou a influência do ferro e do sulfato na digestão anaeróbia do paracetamol. Foram utilizadas garrafas-reator, com lodo anaeróbio, em regime de batelada, com condições distintas de concentração de ferro (25, 142 e 260 mg Fe2+ L-1) e sulfato (210, 601, 993 mg SO4-2 L-1), seguindo um planejamento fatorial 22. Foram analisados, periodicamente, a DQO, concentração do paracetamol e produção de metano. A máxima eficiência de degradação do paracetamol e de produção de metano, 99% e 100%, respectivamente, ocorreu no reator com 260 mg Fe2+ L-1 e 993 mg SO4-2 L-1. Observou-se que existe uma interação entre o ferro e o sulfato e que eles se complementam na degradação da matéria orgânica nos reatores anaeróbios.Acetaminophen is prescribed for different disease. This compound can be found in the environment for inadequate discharge of leftover and expired medicines in wastewater. Biologics systems have been analysed and used like viable alternative in wastewater treatment plants to reduce hydric resource pollution. High efficiency has been observed to remove recalcitrants compounds, like medicines and their derivates, by this kind of system. Therefore, the aim of this study was to analyse the iron and the sulfate influence in acetaminophen anaerobic digestion. Borosilicate bottles were used as batch reactors with anaerobic sludge and distinct condition of iron concentration (25, 142 e 260 mg Fe+2 L-1) and of the sulfate concentration (210, 601, 993 mg SO4-2 L-1) with 22 factorial planning. COD, acetaminophen concentration and methene production were analysed periodically. The high efficiency of acetaminophen degradation and methane production were 99% and 100%, respectively, when 260mgFe+2.L-1 and 993 mg SO4.L-1. A significant interaction between iron and sulfate concentration was observed, and theses compounds assist in anaerobic degradation of the organic matter and increase methane production