732 research outputs found
Renormalization trasformations of the 4D BFYM theory
We study the most general renormalization transformations for the first-order
formulation of the Yang-Mills theory. We analyze, in particular, the trivial
sector of the BRST cohomology of two possible formulations of the model: the
standard one and the extended one. The latter is a promising starting point for
the interpretation of the Yang-Mills theory as a deformation of the topological
BF theory. This work is a necessary preliminary step towards any perturbative
calculation, and completes some recently obtained results.Comment: 12 pages, Late
Testing Noncommutative Spacetimes and Violations of the Pauli Exclusion Principle with underground experiments
We propose to deploy limits that arise from different tests of the Pauli
Exclusion Principle in order: i) to provide theories of quantum gravity with an
experimental guidance; ii) to distinguish among the plethora of possible models
the ones that are already ruled out by current data; iii) to direct future
attempts to be in accordance with experimental constraints. We firstly review
experimental bounds on nuclear processes forbidden by the Pauli Exclusion
Principle, which have been derived by several experimental collaborations
making use of different detector materials. Distinct features of the
experimental devices entail sensitivities on the constraints hitherto achieved
that may differ one another by several orders of magnitude. We show that with
choices of these limits, renown examples of flat noncommutative space-time
instantiations of quantum gravity can be heavily constrained, and eventually
ruled out. We devote particular attention to the analysis of the
-Minkowski and -Minkowski noncommutative spacetimes. These are
deeply connected to some scenarios in string theory, loop quantum gravity and
noncommutative geometry. We emphasize that the severe constraints on these
quantum spacetimes, although cannot rule out theories of top-down quantum
gravity to whom are connected in various way, provide a powerful limitations of
those models that it will make sense to focus on in the future.Comment: 7 pages, 2 figures, updated version accepted in CP
Topological Yang-Mills cohomology in pure Yang-Mills Theory
Using the first order formalism (BFYM) of the Yang-Mills theory we show that
it displays an embedded topological sector corresponding to the field content
of the Topological Yang-Mills theory (TYM). This picture arises after a proper
redefinition of the fields of BFYM and gives a clear representation of the non
perturbative part of the theory in terms of the topological sector. In this
setting the calculation of the of a YM observable is translated into the
calculation of a corresponding (non topological) quantity in TYM. We then
compare the topological observables of TYM with a similar set of observables
for BFYM and discuss the possibility of describing topological observables in
YM theory.Comment: 12 pages, Latex, one reference added, to appear in Phys. Lett.
Duodenal gangliocytic paraganglioma, a rare entity among GEP-NET: a case report with immunohistochemical and molecular study
Gastroenteropancreatic neuroendocrine tumors are the most incident neuroendocrine tumors. In the new WHO classification (2010) the embryological derivation of each neoplastic entity is one of the most important parameters. Gangliocytic Paraganglioma is a tumor originating in the hindgut, a rare neoplasm, generally affecting the second portion of the duodenum, the majority of which are benign. Cases of gangliocytic paraganglioma with local metastasis or local recurrence have also been reported. We describe a GP in a 48-year-old caucasian male with an unusual site (4th portion of duodenum) and an interesting immunohistochemical and molecular pattern. In particular, we examined the expression of some neuroendocrine markers and a marker of neuronal differentiation, NeuroD1, whose expression can help to better understand the nature of this neoplasia. VIRTUAL SLIDES: The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/372095916109680
Linear Accelerator Test Facility at LNF Conceptual Design Report
Test beam and irradiation facilities are the key enabling infrastructures for
research in high energy physics (HEP) and astro-particles. In the last 11 years
the Beam-Test Facility (BTF) of the DA{\Phi}NE accelerator complex in the
Frascati laboratory has gained an important role in the European
infrastructures devoted to the development and testing of particle detectors.
At the same time the BTF operation has been largely shadowed, in terms of
resources, by the running of the DA{\Phi}NE electron-positron collider. The
present proposal is aimed at improving the present performance of the facility
from two different points of view: extending the range of application for the
LINAC beam extracted to the BTF lines, in particular in the (in some sense
opposite) directions of hosting fundamental physics and providing electron
irradiation also for industrial users; extending the life of the LINAC beyond
or independently from its use as injector of the DA{\Phi}NE collider, as it is
also a key element of the electron/positron beam facility. The main lines of
these two developments can be identified as: consolidation of the LINAC
infrastructure, in order to guarantee a stable operation in the longer term;
upgrade of the LINAC energy, in order to increase the facility capability
(especially for the almost unique extracted positron beam); doubling of the BTF
beam-lines, in order to cope with the signicant increase of users due to the
much wider range of applications.Comment: 71 page
Association between β2-adrenoceptor (ADRB2) haplotypes and insulin resistance in PCOS
OBJECTIVE: The aim of this study was to explore β2-adrenoceptor (ADRB2) haplotype associations with phenotypes and quantitative traits related to insulin resistance (IR) and the metabolic syndrome (MS) in a polycystic ovary syndrome (PCOS) population. A secondary purpose was to assess the association between ADRB2 haplotype and PCOS. DESIGN: Genetic polymorphism analysis. Cross-sectional case-control association study. SETTING: Medical University Hospital and research laboratory. PATIENTS: One hundred and sixty-five unrelated women with PCOS and 116 unrelated women without PCOS (control sample). MEASUREMENTS: Clinical and biochemical measurements, and ADRB2 genotyping in PCOS patients and control subjects. METHODS: ADRB2 haplotypes (comprising rs1042711, rs1801704, rs1042713 and rs1042714 in that order), genotyping and statistical analysis to evaluate associations with continuous variables and traits related to IR and MS in a PCOS population. Associations between ADRB2 haplotypes and PCOS were also assessed. RESULTS: We observed an age-adjusted association between ADRB2 haplotype CCGG and lower insulin (P = 0·018) and HOMA (P = 0·008) in the PCOS sample. Interestingly, the expected differences in surrogate measures of IR between cases and controls were not significant in CCGG/CCGG carriers. In the case-control study, genotype CCGG/CCGG was associated with a 14% decrease in PCOS risk (P = 0·043), taking into account confounding variables. CONCLUSIONS: Haplotype I (CCGG) has a protective role for IR and MS in PCOS.Fil: Tellechea, Mariana Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Genética y Biología Molecular; ArgentinaFil: Muzzio, Damián Oscar. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Genética y Biología Molecular; ArgentinaFil: Iglesias Molli, Andrea Elena. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Genética y Biología Molecular; ArgentinaFil: Belli, Susana H.. Hospital Carlos Durand; ArgentinaFil: Graffigna, Mabel N.. Hospital Carlos Durand; ArgentinaFil: Levalle, Oscar A.. Hospital Carlos Durand; ArgentinaFil: Frechtel, Gustavo Daniel. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Genética y Biología Molecular; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Cerrone, Gloria Edith. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Genética y Biología Molecular; Argentin
Vitamin D deficiency in traumatic brain injury and its relationship with severity of injury and quality of life: a prospective, observational study
This single-centre prospective observational study aims to describe the prevalence of vitamin D deficiency (VDD) in the traumatic brain injury (TBI) population and identify any relationship between vitamin D and severity of head injury or quality of life.
124 TBI patients had serum vitamin D (25-OHD) levels measured at the local post-TBI endocrine screening clinic over 20 months. Quality of Life after Brain Injury (QOLIBRI) questionnaires were completed by the patient concurrently. A multivariate regressional analysis was performed, controlling for age, season, ethnicity, time since injury, TBI severity and gender.
34% (n=42) of the cohort were vitamin D deficient (25-OHD <25nmol/L) with a further 23% (n=29) having insufficient levels (25-OHD 25-50nmol/L). Vitamin D was significantly lower in severe TBI compared to mild TBI (n=95, p=0.03, CI 95% -23.60 to -1.21, mean effect size 12.40 nmol/L). There was a trend for self-reported quality of life to be better in patients with optimum vitamin D levels compared to patients with deficient vitamin D levels, controlling for severity of injury (n=81, p=0.05, CI 95% -0.07 to 21.27).
This is the first study to identify a significant relationship between vitamin D levels and severity of head injury. Clinicians should actively screen for and treat VDD in head injured patients to reduce the risk of further morbidity such as osteomalacia and cardiovascular disease. Future research should establish the natural history of vitamin D levels following TBI to identify at which stage VDD develops and whether vitamin D replacement could have a beneficial effect on recovery and quality of life
Analisi e Confronto della Comunicazione Istituzionale - Italia e Regno Unito durante la prima fase della crisi Covid-19
in da quando l\u2019umanit\ue0 ha cominciato a vivere in comunit\ue0 ha dovuto fronteggiare il problema della sanit\ue0 pubblica. Le epidemie sono fenomeni documentati in tutta la storia umana, a partire gi\ue0 dall\u2019Antico Testamento, in cui vengono associate a punizioni divine, mentre le pandemie sono un fenomeno pi\uf9 recente. La pandemia infatti \ue8 definita come una malattia trasmissibile che si diffonde e contagia persone su un areale molto vasto: finch\ue9 le comunit\ue0 umane sono rimaste piccole e distanti, il rischio che una malattia potesse diffondersi in un vasto areale era minimo. Col tempo e l\u2019evolversi delle civilt\ue0 aument\uf2 il livello di interconnessione tra le comunit\ue0, e con esso crebbe anche la capacit\ue0 dei patogeni infettivi nel riuscire a raggiungere popolazioni diverse in zone sempre pi\uf9 vaste: nell\u2019antica Grecia era definita pandemia una malattia che colpiva tutta la penisola ellenica, come la febbre tifoide del V secolo AC; nel medioevo le pandemie colpivano tutta Europa; mentre oggi l\u2019Organizzazione Mondiale della Sanit\ue0 (OMS) definisce \u201cpandemia\u201d una malattia infettiva che si diffonde in tutto il mondo.
Nel Medioevo le pandemie di peste si diffusero principalmente in Europa e in Asia, uccidendo una vasta parte della popolazione del continente e contribuendo a causare gravi crisi sociali ed economiche. La Peste Nera del XIV secolo \ue8, a oggi, la pandemia pi\uf9 letale della storia: la mortalit\ue0 di chi veniva colpito dalla peste era intorno al 50% e la malattia uccise oltre 75 milioni di persone. All\u2019epoca le epidemie non erano eventi sporadici, ma qualcosa di ricorrente, che la popolazione conosceva e temeva. Ci\uf2 era principalmente dovuto alla scarsissima igiene dell\u2019epoca e alle conoscenze mediche molto superficiali e spesso legate a credenze popolari e a rituali religiosi.
Durante il secolo scorso abbiamo assistito all\u2019estendersi della diffusione geografica delle pandemie, gi\ue0 a partire dall\u2019influenza spagnola del 1918-1920, che anche grazie alla Prima Guerra Mondiale riusc\uec a contagiare persone in tutto il mondo, colpendo circa 500 milioni di persone e uccidendone tra i 50 e i 100 milioni , attestandosi come pandemia che ha causato pi\uf9 morti nella storia dell\u2019umanit\ue0 assieme alla Peste Nera.
A dicembre 2020 sono presenti due malattie infettive globali quella dovuta a HIV, cominciata negli anni \u201980 e che ha provocato da allora 32 milioni di morti ; e quella dovuta a SARS-Cov-2, incominciata alla fine del 2019 e che a dicembre 2020 ha colpito quasi 73 milioni di persone, uccidendone pi\uf9 di un milione e mezzo . Queste, assieme all\u2019influenza spagnola del 1918 e a quella suina del 2009, sono le prime pandemie ad avere carattere globale. Oggi le tecnologie sanitarie per fronteggiare queste pandemie sono molto migliori rispetto a qualsiasi altro periodo storico, abbassando la mortalit\ue0 delle malattie, ma \ue8 anche vero che le nostre societ\ue0 sono molto pi\uf9 connesse di un tempo, e la popolazione mondiale in costante crescita rende pi\uf9 semplice la diffusione dei contagi, soprattutto in zone molto popolose e dalle condizioni igieniche e sanitarie scarse
Neutron Majorana mass from exotic instantons
We show how a Majorana mass for the Neutron could result from
non-perturbative quantum gravity effects peculiar to string theory. In
particular, "exotic instantons" in un-oriented string compactifications with
D-branes extending the (supersymmetric) standard model could indirectly produce
an effective operator delta{m} n^t n+h.c. In a specific model with an extra
vector-like pair of `quarks', acquiring a large mass proportional to the string
mass scale (exponentially suppressed by a function of the string moduli
fields), delta{m} can turn out to be as low as 10^{-24}-10^{-25} eV. The
induced neutron-antineutron oscillations could take place with a time scale
tau_{n\bar{n}} > 10^8 s, that could be tested by the next generation of
experiments. On the other hand, proton decay and FCNC's are automatically
strongly suppressed and are compatible with the current experimental limits.
Depending on the number of brane intersections, the model may also lead to the
generation of Majorana masses for R-handed neutrini. Our proposal could also
suggest neutron-neutralino or neutron-axino oscillations, with implications in
UCN, Dark Matter Direct Detection, UHECR and Neutron-Antineutron oscillations.
This suggests to improve the limits on neutron-antineutron oscillations, as a
possible test of string theory and quantum gravity.Comment: 35 pages, 11 figures. More comments on neutron-neutralino mixin
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