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D Comelli

Publications and source records attributed to D Comelli.

12 recordsLinked to original sources
PubMed2001

BLOCH-Nordsieck violation in spontaneously broken Abelian theories.

We point out that, in a spontaneously broken U(1) gauge theory, inclusive processes, whose primary particles are mass eigenstates that do not coincide with the gauge eigenstates, are not free of infrared logarithms. The charge mixing allowed by symmetry breaking and the ensuing Bloch-Nordsieck violation are here analyzed in a few relevant cases and in particular for processes initiated by longitudinal gauge bosons. Of particular interest is the example of weak hypercharge in the standard model where, in addition, left-right mixing effects arise in transversely polarized fermion beams.

Journal Article↗
PubMed2000

Bloch-nordsieck violating electroweak corrections to inclusive TeV scale hard processes

We point out that, since the colliders' initial states ( e(+)e(-),pp, p&pmacr;,ellipsis) carry a definite non-Abelian flavor, electroweak radiative corrections to inclusive hard cross sections at the TeV scale are affected by peculiar Bloch-Nordsieck violating double logs. We recall the setup of soft cancellation theorems, and we analyze the magnitude of the noncanceling terms in the example of electron-positron annihilation into hadrons.

Journal Article↗
PubMed2000

Fluorescence imaging during photodynamic therapy of experimental tumors in mice sensitized with disulfonated aluminum phthalocyanine.

A fluorescence imaging system was used to monitor the emission of disulfonated aluminum phthalocyanine (AlS2Pc) during the photodynamic therapy (PDT) of murine tumors. Cells of the MS-2 fibrosarcoma were injected in mice in two compartments in order to cause the development of tumors in different host tissues. Two drug doses and two uptake times were considered. Moreover, the fluorescence of the AlS2Pc was excited using two wavelengths on the opposite sides of the absorption peak to detect a possible change in the absorption spectrum of the sensitizer induced by the PDT. In the tumors, the treatment induces a variation of the fluorescence intensity: in some mice a mild photobleaching takes place, in others a fluorescence enhancement occurs. Which effect predominates depends on the experimental conditions, even though a large spread of data was found amongst mice of the same group. In all mice, independently of the drug dose, uptake time or tumor compartment, a marked increase in the fluorescence signal takes place at the borders of the irradiated area. To quantify this effect we evaluated the ratio between the fluorescence intensities in the peritumoral area and in the tumor itself. This ratio increases monotonically during the PDT, showing a different behavior with the two excitation wavelengths. This indicates that the AlS2Pc absorption spectrum shifts toward shorter wavelengths as a result of the irradiation.

Animals↗
PubMed1991

[Neuropsychiatric approach to a child with spinal muscular atrophy. A study of relational problems].

Various years' experience of an extensive series of children suffering from progressive chronic spinal muscular atrophy have made it possible to elaborate a neuropsychiatric approach model conducted on the basis of a viewpoint capable of integrating the clinico-medical aspect and aptitude to empathic listening aimed at establishing a therapeutic alliance with the patient. With advancing age and the course of the disease, in most cases very different difficulties and problems are encountered. These change continuously in relation to the stage reached in emotional development. Entry to school and socialisation mark a particular moment in the confrontation with peers and present the ill child with his diversity. With the emergence of adolescent problems, there is also a dramatic new impact between the body image of a wounded, deteriorated self and the evolutionary effort aimed at identifying with the peer group, the autonomisation of parental figures, the integration of a sexed image of the self. Room can be found in this framework for the child neuropsychiatrist who is able to offer himself as a point of reference and set himself up as a model for elaborating disease anxieties. From personal experience it also emerges that in children suffering from a chronic, often fatal disease there is often the need for a physician to coordinate and integrate needs of both a clinical and sociorelational nature for the purpose of allowing the family to get closer to the needs of their child and prevent him from falling prey to destructive type anxieties.

Child↗
PubMedDate not supplied

[Neuropsychiatric development of children with acquired immunodeficiency].

The Authors describe the neuropsychological evolution of 88 children (86 born from HIV infected mothers and, 2 infected by blood products) followed up at the Institute of Infectious Diseases of the University of Pavia. All patients had a clinical, serological and immunologic evaluation done by a pediatric infectivologist and a neurological assessment (Amyeli-Tison and Towen) done by a pediatric neurologist every three months. The Mental Development was examined using the Griffith scales. Electroencephalographic, TC scan, liquor test and other invasive tests were done only in symptomatic patients when indicated. The incidence of Central Nervous System involvement by HIV virus was 24% in infected patients and 37% in children with symptomatic HIV infection; neurological symptoms were observed in coincidence with worsening of AIDS disease. Fifty-five percent of the patients had a serious developmental delays. The Authors stress the importance of an early psychological care of these patients done by a specialist physician in order to reduce the onset of developmental problems in children facing a life expectancy longer than before due to the continuous improvement in the therapeutic management of AIDS.

Acquired Immunodeficiency Syndrome↗