Spectral properties of compact normal quaternionic operators

General, especially spectral, features of compact normal operators in quaternionic Hilbert spaces are studied and some results are established which generalize well-known properties of compact normal operators in complex Hilbert spaces. More precisely, it is proved that the norm of such an operator always coincides with the maximum of the set of absolute values of the eigenvalues (exploiting the notion of spherical eigenvalue). Moreover the structure of the spectral decomposition of a generic compact normal operator $T$ is discussed also proving a spectral characterization theorem for compact normal operators.Comment: 11 pages, no figures. arXiv admin note: text overlap with arXiv:1207.066

Neural Correlates for Apathy: Frontal-Prefrontal and Parietal Cortical- Subcortical Circuits

Apathy is usually defined as the overt manifestation of a lack of motivation, and decreased emotional engagement, lack of concern or indifference, and a flattening of affect. Apathy is a major clinical condition which strongly impacts in every day life events, affects the common daily living abilities, reduced the inner goal directed behavior, and gives the heaviest burden on caregivers. Is a quite common comorbidity of many neurological disease, However, there is no definite consensus on the role of apathy in clinical practice, no definite data on anatomical circuits involved in its development, and no definite instrument to detect it at bedside. As a general observation, the occurrence of apathy is connected to damage of prefrontal cortex (PFC) and basal ganglia; \u201cemotional affective\u201d apathy may be related to the orbitomedial PFC and ventral striatum; \u201ccognitive apathy\u201d may be associated with dysfunction of lateral PFC and dorsal caudate nuclei; deficit of \u201cautoactivation\u201d may be due to bilateral lesions of the internal portion of globus pallidus, bilateral paramedian thalamic lesions, or the dorsomedial portion of PFC. On the other hand, apathy severity has been connected to neurofibrillary tangles density in the anterior cingulate gyrus and to grey matter atrophy in the anterior cingulate (ACC) and in the left medial frontal cortex, confirmed by functional imaging studies. Specifically, these regions are involved in evaluating action and outcomes and, via the basolateral amygdala and nucleus accumbens, feed into an ascending frontostriatal pathway to the dorsolateral prefrontal cortex, which is ultimately responsible for selecting and executing behavioural responses. Damage to the ACC and OFC leads to a disruption of this circuit resulting in impaired decision-making and impaired response initiation, which presents as apathy. Emergent role concerns also the parietal. We will discuss the importance of these circuits in different pathologies, degenerative or vascular, acute or chronic.Apathy is an uncertain nosographical entity, which includes reduced motivation, abulia, decreased empathy, and lack of emotional involvement; it is an important and heavy-burden clinical condition which strongly impacts in everyday life events, affects the common daily living abilities, reduced the inner goal directed behavior, and gives the heaviest burden on caregivers. Is a quite common comorbidity of many neurological disease, However, there is no definite consensus on the role of apathy in clinical practice, no definite data on anatomical circuits involved in its development, and no definite instrument to detect it at bedside. As a general observation, the occurrence of apathy is connected to damage of prefrontal cortex (PFC) and basal ganglia; "emotional affective" apathy may be related to the orbitomedial PFC and ventral striatum; "cognitive apathy" may be associated with dysfunction of lateral PFC and dorsal caudate nuclei; deficit of "autoactivation" may be due to bilateral lesions of the internal portion of globus pallidus, bilateral paramedian thalamic lesions, or the dorsomedial portion of PFC. On the other hand, apathy severity has been connected to neurofibrillary tangles density in the anterior cingulate gyrus and to gray matter atrophy in the anterior cingulate (ACC) and in the left medial frontal cortex, confirmed by functional imaging studies. These neural networks are linked to projects, judjing and planning, execution and selection common actions, and through the basolateral amygdala and nucleus accumbens projects to the frontostriatal and to the dorsolateral prefrontal cortex. Therefore, an alteration of these circuitry caused a lack of insight, a reduction of decision-making strategies, and a reduced speedness in action decision, major responsible for apathy. Emergent role concerns also the parietal cortex, with its direct action motivation control. We will discuss the importance of these circuits in different pathologies, degenerative or vascular, acute or chronic

gcodeml: A Grid-enabled Tool for Detecting Positive Selection in Biological Evolution

One of the important questions in biological evolution is to know if certain changes along protein coding genes have contributed to the adaptation of species. This problem is known to be biologically complex and computationally very expensive. It, therefore, requires efficient Grid or cluster solutions to overcome the computational challenge. We have developed a Grid-enabled tool (gcodeml) that relies on the PAML (codeml) package to help analyse large phylogenetic datasets on both Grids and computational clusters. Although we report on results for gcodeml, our approach is applicable and customisable to related problems in biology or other scientific domains.Comment: 10 pages, 4 figures. To appear in the HealthGrid 2012 con

Metastatic angioimmunoblastic T-cell lymphoma started from thoracic paravertebral region: a Case report

Angioimmunoblastic T-cell lymphoma (AITL) is one of the most frequent nodal T-cell lymphoma. 1,2 It derives from follicular helper T-cell (TFH).3 It accounts for 15 - 20% of all peripheral T-cell lymphomas and usually affects patients in the seventh decade of life.1,2,4,5 AITL\u2019s incidence is nearly 0,05 new patient case per 100,000 people in US, and there\u2019s no sex predilection.6,7 It is characterized by polymorphic lymph node infiltrate with a prominent proliferation of high endothelial venules and follicular dendritic cells, different immune disorders and a poor prognosis. 8,9 The neoplastic T-cells express CD2, CD3, CD4 and CD10 but the marker\u2019s specificity has been debated. More specific indicators of AITL are CXCL-13, programmed death-1 (PD1), inducible costimulator (ICOS), and BCL6 transcription factor.10-12 Nearly all patients have EBV-infected B cells in their lymph nodes, but the presence of these EBV-positive cells doesn\u2019t correlate with survival.13-15 However, the role of EBV isn\u2019t clear yet: it could be secondary to the immune deregulation, or it could be a fundamental factor involved in disease\u2019s start and progression. AITL is frequently associated with polyclonal B-cell or plasma cell proliferation;8 this neoplastic proliferation of B-cells on parallel with AITL could be motivated by a cluster of pluripotent cells with the ability to differentiate into B-cells and T-cells neoplasm simultaneously, maybe due to exposition to pharmacological therap\ue8ies or specific mutagens. Clinical manifestations are often represented by group-B symptoms (fever, night sweats, weight loss), hepatosplenomegaly, anemia, lymphadenopathy, polyclonal hypergammaglobulinemia, thrombocytopenia and/or a large variety of immune disorders.16,17 Up to 50% of develop cutaneous lesions, expression of extranodal diffusion of the tumor: urticaria, purpura, pruritic maculopapular eruptions, erosions, plaques, nodules, petechiae.18-20 Despite occasionally spontaneous remissions,21 AITL prognosis is poor, with a median overall survival of 3 years