Geometry of contours and Peierls estimates in d=1 Ising models

Following Fr\"ohlich and Spencer, we study one dimensional Ising spin systems with ferromagnetic, long range interactions which decay as $|x-y|^{-2+\alpha}$, $0\leq \alpha\leq 1/2$. We introduce a geometric description of the spin configurations in terms of triangles which play the role of contours and for which we establish Peierls bounds. This in particular yields a direct proof of the well known result by Dyson about phase transitions at low temperatures.Comment: 28 pages, 3 figure

SOCIAL REFERENCING AND UNDERSTANDING OF HUMAN EMOTIONAL EXPRESSIONS IN DOGS

Summary Social referencing and understanding of human emotional expressions in dogs. Introduction The literature on dog cognition and in particular social cognition has grown incredibly in recent years, however no studies have focused on the process of Social referencing in dog-human communication and interaction, and only few preliminary studies have investigated dogs\u2019 understanding of human emotions. Social referencing is a process characterized by the use of another person\u2019s perceptions and interpretation of a situation to form one\u2019s own understanding and guide action. Human infants use this process to go beyond the information given by an informant to construct a more general interpretation of the meaning of a stimulus and they can successfully link the emotions expressed to a referent object. Social referencing has been investigated not only in humans, but also in a few primate species, namely chimpanzees and barbary macaques, although with mixed results. In fact, results from primate studies are overall ambiguous, with the strongest evidence of social referencing coming from human-raised chimpanzees, where it is exhibited with their human caretaker. There is, however, more consistent evidence that non-human primates can refer conspecific and human emotional expressions to a referent object. The dog-human relationship is a very special one and the more recent literature shows that the dog-human bond is similar in many respect to an infantile attachment. Furthermore, studies suggest that dogs are sensitive to a number of behaviours potentially revealing the person\u2019s attentional states; can follow a number of human referential cues, and, preliminary evidence, seems to suggest that they can also discriminate between some expressions of human emotions. Finally there is also some evidence that dogs can communicate intentionally and referentially with humans (although this is still a mater of some controversy). Considering the above, dogs are particularly good candidates for the comparative investigation of social referencing and of the ability to understand human\u2019s emotional expressions as referring to specific objects. Four studies are presented in this thesis which aimed to investigate Social referencing in dog-human dyads and dogs\u2019 capacity to understand the referential nature of a person\u2019s emotional message. The aims of the present research were to add to the literature on dogs\u2019 socio-cognitive abilities and of human-dog communication by studying (1) the presence of Social referencing, both referential looking and behavioural regulation, in dogs towards humans, (2) the potential selectivity of this process, based on the relationship with the informant (owner vs. stranger), (3) the effect of a particular kind of training experiences (i.e. water rescue training) on this process, and (4) the ability of dogs to refer different emotional expressions toward two objects. To answer these questions we carried out four different experiments: Study 1 Social referencing in dog-human dyads was investigated using the \u201cnew object paradigm\u201d. As no study has been carried out on dogs on this topic so far, we set up a new procedure suitable to this species, that was similar to the one used in the infant. In particular in our \u201cnew object paradigm\u201d we presented dogs with a new and potentially scary object (a fan with plastic ribbons attached to it) in presence of their owner as the informant. The aim was to evaluate whether, in a social referencing paradigm, dogs would show referential looking and behavioural regulation toward the owner acting as the informant and hence approach the object more having witnessed a positive vs. a negative message. We tested 75 dog-owner dyads at the Canis Sapiens Lab of the University of Milan. There were two different groups of dogs: in one group the owner was delivering a positive emotional message towards the object, whereas in the second group the owner delivered a negative emotional message. The results of this first study showed that dogs, like human infants, use referential looking towards a familiar person (their owner) in a situation of ambiguity. However, differently from infants, dogs showed no clear evidence of behavioural regulation after receiving an emotional message from the owner. Study 2 Since the results obtained in the first study showed a clear presence of referential looking in dogs, but not clear evidence of behavioural regulation toward the owner, we modified the testing procedure to further evaluate behavioural regulation. We investigated the presence of Social referencing in dogs with the same potentially scary object (a fan with plastic ribbons attached on it) in presence of their owner vs. a stranger. The study had two main aims. First, since results obtained in the first study provided only unclear evidence of behavioural regulation toward the object, we wanted to see whether using a procedure more closely resembling the one used with infants we would be able to find evidence of behavioural regulation. The second aim was to assess the influence of the informant\u2019s identity on social referencing. Selectivity is an important aspect of children\u2019s Social referencing: they seem to use referential looking toward both a familiar and an unfamiliar person, but they regulate their behaviour only when a familiar person is the informant or when she/he is present in the experimental set-up together with the unfamiliar informant. We tested 90 dog-owner dyads and there were four groups of dogs: two groups were tested with the owner as the informant (either expressing a positive or a negative emotion), and two were tested with a stranger as informant (either expressing a positive or a negative emotion). Results provided clear evidence that dogs use referential looking not only towards their owner but also towards a stranger, with no difference between the two persons. Furthermore, dogs regulated their behaviour towards the object after receiving a positive or a negative emotional expression by the owner, but not when the stranger was acting as the informant. Study 3 Since in Study 2, besides referential looking, we found a clear evidence of behavioural regulation with the owner, whereas no clear results emerged with the stranger acting as the informant, we tested dogs exposed to a particular type of training: water rescue dogs. In fact, during their training these dogs become used to focusing their attention on unfamiliar person. Thus we investigated the presence of Social referencing in dog-human dyads using the same procedure and scary object as in study 2 but with a stranger acting as the informant. For this study we tested 22 dog-owner dyads: the group of trained water rescue dogs were tested with their owners in Naples (Universit\ue0 degli Studi di Napoli \u201cFederico II\u201d), while the breed, age and sex matched control group was tested in Milano at the Canis Sapiens Lab of the University. Dogs of both groups showed referential looking toward the stranger and this result supports those obtained in study 2. However, highly trained water rescue dogs did not change their behaviour towards the object (behavioural regulation) when the stranger was exhibiting a positive emotional expression towards it. Surprisingly, the control (untrained) group dogs did change their behaviour toward the ambiguous object, approaching it more than the trained dogs when the positive emotional message was given by the stranger. These findings are discussed in relation to our previous results (in Study 2) where no such effect was found with the stranger acting as the informant (we believe the likely cause is the breed of dogs tested in Study 3) and in relation to the potential inhibitory effect of training on dogs\u2019 behavioural regulation in this context. Study 4 In the previous three studies dogs were tested always in the presence of only one object (the potentially scary fan), and, although the informant\u2019s message always referred to that object, the goal of these studies was not strictly to assess whether dogs were capable of appropriately referring the human\u2019s emotional expression to the object itself. So far only one study has tested dogs\u2019 ability to attribute a human\u2019s emotional reaction (facial expression and short vocalization) to a specific object (i.e. to grasp that emotions can be referred to something in the outside world). Thus the aim of this study was to assess dog\u2019s understanding of human emotional expression as referential. In particular, we evaluated if dogs can discriminate between three different emotional expressions (fear, happiness and neutral) and whether they have a perception that a human\u2019s (owner vs. stranger) emotional expression can refer to specific objects in the environment. We tested 95 dog-owner dyads at the Canis Sapiens Lab of the University of Milan. We adapted a procedure used with infants, and more recently also with chimpanzees and dogs, in which the informant expresses two different emotions towards two identical (hidden) objects. In a control group, the same procedure is adopted but in the absence of the objects (\u201cno-object\u201d condition). After observing the emotional expressions being conveyed by the informant (owner vs. stranger) dogs were free to approach the objects. Dogs showed a clear preference for the hidden object eliciting the positive emotion, compared to one eliciting the negative one when the owner was acting; on the contrary no preference emerged when the stranger was acting as informant. Furthermore, dogs didn\u2019t show a choice behaviour when the owner was expressing the emotion in the \u201cno-object condition\u201d. A follow-up study, contrasting the positive and negative emotion in turn with a neutral one, showed that dogs tended to approach the object eliciting a positive emotion rather than avoid the one eliciting a negative reaction. Taken together these results, show that dogs do in fact appreciate that an emotional message can relate to a specific object if the owner is the informant but they do not do so if the stranger is the informant. Furthermore, their performance seems to be based on approaching the positive stimulus rather than avoiding the negative one. Together these results suggest that prior experience with their owner using positive emotional expressions, has allowed dogs to associate these emotions to particular objects. Finally, considering the non-specific behaviours exhibited by dogs in the no-object control group, dogs may even have come to expect that an emotional message refers to a specific object. Conclusions The experiments presented in the current thesis reveal some new and interesting aspects of dog social cognition and communication with humans. On the one hand they provide the first evidence of social referencing in dogs: they show that dogs, like infants, can show referential looking and behavioural regulation in ambiguous situations when the emotional message is delivered by the owner, or by a stranger (in presence of the owner). Finally, these findings suggest that dogs have some understanding that emotional expressions are referential, in the sense of being directed to specific stimuli in the environment as has been reported for infants and non human primates

A Novel Hierarchy of Integrable Lattices

In the framework of the reduction technique for Poisson-Nijenhuis structures, we derive a new hierarchy of integrable lattice, whose continuum limit is the AKNS hierarchy. In contrast with other differential-difference versions of the AKNS system, our hierarchy is endowed with a canonical Poisson structure and, moreover, it admits a vector generalisation. We also solve the associated spectral problem and explicity contruct action-angle variables through the r-matrix approach.Comment: Latex fil

Deep learning-based parameter mapping for joint relaxation and diffusion tensor MR Fingerprinting

Magnetic Resonance Fingerprinting (MRF) enables the simultaneous quantification of multiple properties of biological tissues. It relies on a pseudo-random acquisition and the matching of acquired signal evolutions to a precomputed dictionary. However, the dictionary is not scalable to higher-parametric spaces, limiting MRF to the simultaneous mapping of only a small number of parameters (proton density, T1 and T2 in general). Inspired by diffusion-weighted SSFP imaging, we present a proof-of-concept of a novel MRF sequence with embedded diffusion-encoding gradients along all three axes to efficiently encode orientational diffusion and T1 and T2 relaxation. We take advantage of a convolutional neural network (CNN) to reconstruct multiple quantitative maps from this single, highly undersampled acquisition. We bypass expensive dictionary matching by learning the implicit physical relationships between the spatiotemporal MRF data and the T1, T2 and diffusion tensor parameters. The predicted parameter maps and the derived scalar diffusion metrics agree well with state-of-the-art reference protocols. Orientational diffusion information is captured as seen from the estimated primary diffusion directions. In addition to this, the joint acquisition and reconstruction framework proves capable of preserving tissue abnormalities in multiple sclerosis lesions

Quality control for more reliable integration of deep learning-based image segmentation into medical workflows

Machine learning algorithms underpin modern diagnostic-aiding software, whichhas proved valuable in clinical practice, particularly in radiology. However,inaccuracies, mainly due to the limited availability of clinical samples fortraining these algorithms, hamper their wider applicability, acceptance, andrecognition amongst clinicians. We present an analysis of state-of-the-artautomatic quality control (QC) approaches that can be implemented within thesealgorithms to estimate the certainty of their outputs. We validated the mostpromising approaches on a brain image segmentation task identifying whitematter hyperintensities (WMH) in magnetic resonance imaging data. WMH are acorrelate of small vessel disease common in mid-to-late adulthood and areparticularly challenging to segment due to their varied size, anddistributional patterns. Our results show that the aggregation of uncertaintyand Dice prediction were most effective in failure detection for this task.Both methods independently improved mean Dice from 0.82 to 0.84. Our workreveals how QC methods can help to detect failed segmentation cases andtherefore make automatic segmentation more reliable and suitable for clinicalpractice.<br

Revisiting protein aggregation as pathogenic in sporadic Parkinson and Alzheimer diseases.

The gold standard for a definitive diagnosis of Parkinson disease (PD) is the pathologic finding of aggregated α-synuclein into Lewy bodies and for Alzheimer disease (AD) aggregated amyloid into plaques and hyperphosphorylated tau into tangles. Implicit in this clinicopathologic-based nosology is the assumption that pathologic protein aggregation at autopsy reflects pathogenesis at disease onset. While these aggregates may in exceptional cases be on a causal pathway in humans (e.g., aggregated α-synuclein in SNCA gene multiplication or aggregated β-amyloid in APP mutations), their near universality at postmortem in sporadic PD and AD suggests they may alternatively represent common outcomes from upstream mechanisms or compensatory responses to cellular stress in order to delay cell death. These 3 conceptual frameworks of protein aggregation (pathogenic, epiphenomenon, protective) are difficult to resolve because of the inability to probe brain tissue in real time. Whereas animal models, in which neither PD nor AD occur in natural states, consistently support a pathogenic role of protein aggregation, indirect evidence from human studies does not. We hypothesize that (1) current biomarkers of protein aggregates may be relevant to common pathology but not to subgroup pathogenesis and (2) disease-modifying treatments targeting oligomers or fibrils might be futile or deleterious because these proteins are epiphenomena or protective in the human brain under molecular stress. Future precision medicine efforts for molecular targeting of neurodegenerative diseases may require analyses not anchored on current clinicopathologic criteria but instead on biological signals generated from large deeply phenotyped aging populations or from smaller but well-defined genetic-molecular cohorts

Moraxella catarrhalis evades neutrophil oxidative stress responses providing a safer niche for nontypeable Haemophilus influenzae

Moraxella catarrhalis and nontypeable Haemophilus influenzae (NTHi) are pathogenic bacteria frequently associated with exacerbation of chronic obstructive pulmonary disease (COPD), whose hallmark is inflammatory oxidative stress. Neutrophils produce reactive oxygen species (ROS) which can boost antimicrobial response by promoting neutrophil extracellular traps (NET) and autophagy. Here, we showed that M. catarrhalis induces less ROS and NET production in differentiated HL-60 cells compared to NTHi. It is also able to actively interfere with these responses in chemically activated cells in a phagocytosis and opsonin-independent and contact-dependent manner, possibly by engaging host immunosuppressive receptors. M. catarrhalis subverts the autophagic pathway of the phagocytic cells and survives intracellularly. It also promotes the survival of NTHi which is otherwise susceptible to the host antimicrobial arsenal. In-depth understanding of the immune evasion strategies exploited by these two human pathogens could suggest medical interventions to tackle COPD and potentially other diseases in which they co-exist