476 research outputs found
Contextual, Optimal and Universal Realization of the Quantum Cloning Machine and of the NOT gate
A simultaneous realization of the Universal Optimal Quantum Cloning Machine
(UOQCM) and of the Universal-NOT gate by a quantum injected optical parametric
amplification (QIOPA), is reported. The two processes, forbidden in their exact
form for fundamental quantum limitations, are found universal and optimal, and
the measured fidelity F<1 is found close to the limit values evaluated by
quantum theory. This work may enlighten the yet little explored
interconnections of fundamental axiomatic properties within the deep structure
of quantum mechanics.Comment: 10 pages, 2 figure
Photon mass and electrogenesis
We show that if photon possesses a tiny but non-vanishing mass the universe
cannot be electrically neutral. Cosmological electric asymmetry could be
generated either at an early stage by different evaporation rates of primordial
black holes with respect to positively and negatively charged particles or by
predominant capture of protons in comparison to electrons by heavy galactic
black holes in contemporary universe. An impact of this phenomenon on the
generation of large scale magnetic fields and on the universe acceleration is
considered.Comment: 15 pages, no figures, text added, typos corrected, refs. improve
Genetic pre-participation screening in selected athletes: a new tool for the prevention of sudden cardiac death?
Sudden cardiac death (SCD) of athletes is a
topical issue. “Borderline cardiac abnormalities”, which occur in
~2% of elite male athletes, may result in SCD, which may have
a genetic base. Genetic analysis may help identify pathological
cardiac abnormalities. We performed phenotype-guided
genetic analysis in athletes who, pre-participation, showed
ECG and/or echo “borderline” abnormalities, to discriminate
subjects at a greater risk of SCD.
Methods: We studied 24 elite athletes referred by the National
Federation of Olympic sports; and 25 subjects seeking eligibility
to practice agonistic sport referred by the Osservatorio
Epidemiologico della Medicina dello Sport della Regione
Campania. Inclusion criteria: a) ECG repolarization borderline
abnormalities; b) benign ventricular arrhythmias; c) left
ventricular wall thickness in the grey zone of physiology versus
pathology (max wall thickness 12-15 mm in females; 13-16 mm
in males). Based on the suspected phenotype, we screened
subjects for the LMNA gene, for 8 sarcomeric genes, 5
desmosomal genes, and cardiac calcium, sodium and
potassium channel disease genes.
Results: Genetic analysis was completed in 37/49 athletes, 22
competitive and 27 non-competitive athletes, showing
“borderline” clinical markers suggestive of hypertrophic
cardiomyopathy (HCM,n. 24), dilated cardiomyopathy (n. 4),
arrhythmogenic right ventricular dysplasia/cathecholaminergic
polymorphic ventricular tachycardia (ARVD/CPVT, n. 11), long
QT syndrome (LQTS, n. 4), sick sinus syndrome (SSS, n. 5),
Brugada syndrome (BrS, n. 1). We identifyed 11 mutations in
9 athletes (an ARVD athlete was compound heterozygote for
the PKP2 gene and an HCM athlete was double heterozygote
for the MYBPC3 and TNNT2 genes): 3 known mutations
related to LQTS, HCM and ARVD, respectively, and 8 novel
mutations, located in the SCN5A, RyR2, PKP2, MYBPC3 and
ACTC1 genes. The new mutations were absent in ~800 normal
chromosomes and were predicted “probably damaging” by in
silico analysis. Patch clamp analysis in channelopathies
indicated for some mutation abnormal biophysical behavior of
the corresponding mutant protein.
Conclusion: Genetic analysis may help distinguish between
physiology and pathology in athletes with clinically suspected
heart disease
Selenotriapine – An isostere of the most studied thiosemicarbazone with pronounced pro-apoptotic activity, low toxicity and ability to challenge phenotype reprogramming of 3-D mammary adenocarcinoma tumors
Triapine, the most studied α-N-heterocyclic thiosemicarbazone, revealed potent activity against advanced leukemia, but was ineffective against a variety of solid tumors. Moreover, methemoglobinemia, which is a side effect of triapine administration, may limits all clinical application. To enhance anticancer activity and reduce side effects, we applied an isosteric replacement of sulfur to selenium atom was performed by synthesis and characterization of selenium triapine analog, 3-aminopyridine-2-carboxaldehyde selenosemicarbazone (selenotriapine). Compared to triapine, selenotriapine revealed superior pro-apoptotic activity with activation of intrinsic apoptotic pathway in both human monocytic leukemia (THP-1) and mammary adenocarcinoma (MCF-7) cell lines. For MCF-7 2-D cultures, selenotriapine induced notable increase in mitochondrial superoxide radical generation and dissipation of mitochondrial transmembrane potential. A significant delay in growth of MCF-7 spheroids (3-D culture) was accompanied by phenotypic stem cell reprogramming (Oct-4 expression). Additionally, selenotriapine demonstrated a very low toxicity profile as compared to triapine, confirmed over alleviated extent of methemoglobin formation and higher IC50 value in brine shrimp cytotoxicity assay
Abnormal ECG Findings in Athletes: Clinical Evaluation and Considerations.
PURPOSE OF REVIEW: Pre-participation cardiovascular evaluation with electrocardiography is normal practice for most sporting bodies. Awareness about sudden cardiac death in athletes and recognizing how screening can help identify vulnerable athletes have empowered different sporting disciplines to invest in the wellbeing of their athletes. RECENT FINDINGS: Discerning physiological electrical alterations due to athletic training from those representing cardiac pathology may be challenging. The mode of investigation of affected athletes is dependent on the electrical anomaly and the disease(s) in question. This review will highlight specific pathological ECG patterns that warrant assessment and surveillance, together with an in-depth review of the recommended algorithm for evaluation
Scalar field instability in de Sitter space-time
Starting from the equation of motion of the quantum operator of a real scalar
field phi in de Sitter space-time, a simple differential equation is derived
which describes the evolution of quantum fluctuations of this field.
Full de Sitter invariance is assumed and no ad hoc infrared cutoff is
introduced. This equation is solved explicitly and in massive case our result
agrees with the standard one. In massless case the large time behavior of our
solution differs by sign from the expression found in earlier papers. A
possible cause of discrepancy may be a spontaneous breaking of de Sitter
invariance.Comment: 20 pages, no figures, revtex4. V2: minor changes, references adde
Gribov Problem for Gauge Theories: a Pedagogical Introduction
The functional-integral quantization of non-Abelian gauge theories is
affected by the Gribov problem at non-perturbative level: the requirement of
preserving the supplementary conditions under gauge transformations leads to a
non-linear differential equation, and the various solutions of such a
non-linear equation represent different gauge configurations known as Gribov
copies. Their occurrence (lack of global cross-sections from the point of view
of differential geometry) is called Gribov ambiguity, and is here presented
within the framework of a global approach to quantum field theory. We first
give a simple (standard) example for the SU(2) group and spherically symmetric
potentials, then we discuss this phenomenon in general relativity, and recent
developments, including lattice calculations.Comment: 24 pages, Revtex 4. In the revised version, a statement has been
amended on page 11, and References 14, 16 and 27 have been improve
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