154 research outputs found
Anomalous dimensions of leading twist conformal operators
We extend and develop a method for perturbative calculations of anomalous
dimensions and mixing matrices of leading twist conformal primary operators in
conformal field theories. Such operators lie on the unitarity bound and hence
are conserved (irreducible) in the free theory. The technique relies on the
known pattern of breaking of the irreducibility conditions in the interacting
theory. We relate the divergence of the conformal operators via the field
equations to their descendants involving an extra field and accompanied by an
extra power of the coupling constant. The ratio of the two-point functions of
descendants and of their primaries determines the anomalous dimension, allowing
us to gain an order of perturbation theory. We demonstrate the efficiency of
the formalism on the lowest-order analysis of anomalous dimensions and mixing
matrices which is required for two-loop calculations of the former. We compare
these results to another method based on anomalous conformal Ward identities
and constraints from the conformal algebra. It also permits to gain a
perturbative order in computations of mixing matrices. We show the complete
equivalence of both approaches.Comment: 21 pages, 4 figures; references adde
Evaluation of the association between lifestyle risk factors for myopia development and the prevalence of nearsightedness among young adults
Is DNA methylation in the brain a mechanism of alcohol use disorder?
Alcohol use disorder (AUD) is a worldwide problem. Unfortunately, the molecular mechanisms of alcohol misuse are still poorly understood, therefore successful therapeutic approaches are limited. Accumulating data indicate that the tendency for compulsive alcohol use is inherited, suggesting a genetic background as an important factor. However, the probability to develop AUD is also affected by life experience and environmental factors. Therefore, the epigenetic modifications that are altered over lifetime likely contribute to increased risk of alcohol misuse. Here, we review the literature looking for the link between DNA methylation in the brain, a common epigenetic modification, and AUD-related behaviors in humans, mice and rats. We sum up the main findings, identify the existing gaps in our knowledge and indicate future directions of the research
Operator mixing in N=4 SYM: The Konishi anomaly revisited
In the context of the superconformal N=4 SYM theory the Konishi anomaly can
be viewed as the descendant of the Konishi multiplet in the 10 of
SU(4), carrying the anomalous dimension of the multiplet. Another descendant
with the same quantum numbers, but this time without anomalous
dimension, is obtained from the protected half-BPS operator (the
stress-tensor multiplet). Both and are renormalized mixtures
of the same two bare operators, one trilinear (coming from the superpotential),
the other bilinear (the so-called "quantum Konishi anomaly"). Only the operator
is allowed to appear in the right-hand side of the Konishi anomaly
equation, the protected one does not match the conformal properties of
the left-hand side. Thus, in a superconformal renormalization scheme the
separation into "classical" and "quantum" anomaly terms is not possible, and
the question whether the Konishi anomaly is one-loop exact is out of context.
The same treatment applies to the operators of the BMN family, for which no
analogy with the traditional axial anomaly exists. We illustrate our abstract
analysis of this mixing problem by an explicit calculation of the mixing matrix
at level g^4 ("two loops") in the supersymmetric dimensional reduction scheme.Comment: 28 pp LaTeX, 3 figure
Bolesław Wicherkiewicz and his role in the development of new cataract surgery techniques in the late XIX century
Does Small Ruminant Lentivirus Infection in Goats Predispose to Bacterial Infection of the Mammary Gland? A Preliminary Study
The aim of this study was to determine whether asymptomatic small ruminant lentivirus
seropositive (SRLV-SP) goats were more susceptible to bacterial infection of the udder when lactating
by comparing the presence and species of pathogenic bacteria in their milk with the values for
seronegative goats (SRLV-SN). Milk samples were collected during morning milking on days 20, 40,
60, 150, and 210 of lactation for three consecutive years and subjected to bacteriological examination.
Staphylococcus caprae and S. xylosus were the most frequent strains identified in both SRLV-SP and
SRLV-SN goats. The prevalence of pathogenic bacteria was the highest in the 1st lactation, regardless
of SRLV status. Moreover, the prevalence of pathogenic bacteria was significantly higher in SRLV-SP
goats, but only those in the 5th or further lactation (p = 0.010). This suggests a relationship between
long-lasting SRLV infection and susceptibility to bacterial infections of the udder
A three-loop test of the dilatation operator in N=4 SYM
We compute the three-loop anomalous dimension of the BMN operators with
charges J=0 (the Konishi multiplet) and J=1 in N=4 super-Yang-Mills theory. We
employ a method which effectively reduces the calculation to two loops. Instead
of using the superconformal primary states, we consider the ratio of the
two-point functions of suitable descendants of the corresponding multiplets.
Our results unambiguously select the form of the N=4 SYM dilatation operator
which is compatible with BMN scaling. Thus, we provide evidence for BMN scaling
at three loops.Comment: 38 pages LaTeX, 4 figures, references adde
On twist-two operators in N=4 SYM
We propose a mechanism for calculating anomalous dimensions of higher-spin
twist-two operators in N=4 SYM. We consider the ratio of the two-point
functions of the operators and of their superconformal descendants or,
alternatively, of the three-point functions of the operators and of the
descendants with two protected half-BPS operators. These ratios are
proportional to the anomalous dimension and can be evaluated at n-1 loop in
order to determine the anomalous dimension at n loops. We illustrate the method
by reproducing the well-known one-loop result by doing only tree-level
calculations. We work out the complete form of the first-generation descendants
of the twist-two operators and the scalar sector of the second-generation
descendants.Comment: references added; typos correcte
Epigenetic activation of antiviral sensors and effectors of interferon response pathways during SARS-CoV-2 infection
Recent studies have shown that methylation changes identified in blood cells of COVID-19 patients have a po-tential to be used as biomarkers of SARS-CoV-2 infection outcomes. However, different studies have reported different subsets of epigenetic lesions that stratify patients according to the severity of infection symptoms, and more importantly, the significance of those epigenetic changes in the pathology of the infection is still not clear. We used methylomics and transcriptomics data from the largest so far cohort of COVID-19 patients from four geographically distant populations, to identify casual interactions of blood cells' methylome in pathology of the COVID-19 disease. We identified a subset of methylation changes that is uniformly present in all COVID-19 patients regardless of symptoms. Those changes are not present in patients suffering from upper respiratory tract infections with symptoms similar to COVID-19. Most importantly, the identified epigenetic changes affect the expression of genes involved in interferon response pathways and the expression of those genes differs be-tween patients admitted to intensive care units and only hospitalized. In conclusion, the DNA methylation changes involved in pathophysiology of SARS-CoV-2 infection, which are specific to COVID-19 patients, can not only be utilized as biomarkers in the disease management but also present a potential treatment target
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