418 research outputs found
Four-nucleon contact interactions from holographic QCD
We calculate the low energy constants of four-nucleon interactions in an
effective chiral Lagrangian in holographic QCD. We start with a D4-D8 model to
obtain meson-nucleon interactions and then integrate out massive mesons to
obtain the four-nucleon interactions in 4D. We end up with two low energy
constants at the leading order and seven of them at the next leading order,
which is consistent with the effective chiral Lagrangian. The values of the low
energy constants are evaluated with the first five Kaluza-Klein resonances.Comment: 28 page
Bidirectional Transcription Directs Both Transcriptional Gene Activation and Suppression in Human Cells
Small RNAs targeted to gene promoters in human cells have been shown to modulate both transcriptional gene suppression and activation. However, the mechanism involved in transcriptional activation has remained poorly defined, and an endogenous RNA trigger for transcriptional gene silencing has yet to be identified. Described here is an explanation for siRNA-directed transcriptional gene activation, as well as a role for non-coding antisense RNAs as effector molecules driving transcriptional gene silencing. Transcriptional activation of p21 gene expression was determined to be the result of Argonaute 2–dependent, post-transcriptional silencing of a p21-specific antisense transcript, which functions in Argonaute 1–mediated transcriptional control of p21 mRNA expression. The data presented here suggest that in human cells, bidirectional transcription is an endogenous gene regulatory mechanism whereby an antisense RNA directs epigenetic regulatory complexes to a sense promoter, resulting in RNA-directed epigenetic gene regulation. The observations presented here support the notion that epigenetic silencing of tumor suppressor genes, such as p21, may be the result of an imbalance in bidirectional transcription levels. This imbalance allows the unchecked antisense RNA to direct silent state epigenetic marks to the sense promoter, resulting in stable transcriptional gene silencing
Is soft breaking of BRST symmetry consistent?
A definition of soft breaking of BRST symmetry in the field-antifield
formalism is proposed, valid for general gauge theories and arbitrary gauge
fixing. The Ward identities for the generating functionals of Green's functions
are derived, and their gauge dependence is investigated. We discuss the
Gribov-Zwanziger action for the one-parameter family of R_xi gauges. It is
argued that gauge theories with a soft breaking of BRST symmetry are
inconsistent.Comment: 1+16 pages; v2: example of section 5 changed to R_xi gauges; v3:
small corrections to section 5, one reference added, published versio
Nonthermal Emission from Star-Forming Galaxies
The detections of high-energy gamma-ray emission from the nearby starburst
galaxies M82 & NGC253, and other local group galaxies, broaden our knowledge of
star-driven nonthermal processes and phenomena in non-AGN star-forming
galaxies. We review basic aspects of the related processes and their modeling
in starburst galaxies. Since these processes involve both energetic electrons
and protons accelerated by SN shocks, their respective radiative yields can be
used to explore the SN-particle-radiation connection. Specifically, the
relation between SN activity, energetic particles, and their radiative yields,
is assessed through respective measures of the particle energy density in
several star-forming galaxies. The deduced energy densities range from O(0.1)
eV/cm^3 in very quiet environments to O(100) eV/cm^3 in regions with very high
star-formation rates.Comment: 17 pages, 5 figures, to be published in Astrophysics and Space
Science Proceeding
One moment, please: can the speed and quality of political contact affect democratic health
Contact between politicians and their constituents is the cornerstone of democracies globally but an area of scholarship that remains relatively underdeveloped. Political contact can help convey authority, provide legitimacy and facilitate governance. This article goes beyond the assumption that representatives need to communicate more with the public and suggests, instead, that the quality of contact matters. Focusing on four processes by which citizens can contact their representatives (face-to-face, by letter, email or social media), we employ an experimental vignette methodology to test whether the character and timeliness of politicians’ responses to citizen communication affects two indicators of democratic health: (a) the latter’s satisfaction with political contact and (b) their likelihood to re-contact representatives. Our findings provide evidence that personalised communication and to a smaller extent, speed of response, can influence citizen satisfaction and their likelihood of re-engagement. This suggests politicians can improve these indicators of democratic health by adjusting the style of political contact and communication
Positron emission mammography in breast cancer presurgical planning: comparisons with magnetic resonance imaging
Rapid tests and urine sampling techniques for the diagnosis of urinary tract infection (UTI) in children under five years: a systematic review
Background: Urinary tract infection (UTI) is one of the most common sources of infection in children under five. Prompt diagnosis and treatment is important to reduce the risk of renal scarring. Rapid, cost-effective, methods of UTI diagnosis are required as an alternative to culture. Methods: We conducted a systematic review to determine the diagnostic accuracy of rapid tests for detecting UTI in children under five years of age. Results: The evidence supports the use of dipstick positive for both leukocyte esterase and nitrite (pooled LR+ = 28.2, 95% CI: 17.3, 46.0) or microscopy positive for both pyuria and bacteriuria (pooled LR+ = 37.0, 95% CI: 11.0, 125.9) to rule in UTI. Similarly dipstick negative for both LE and nitrite (Pooled LR- = 0.20, 95% CI: 0.16, 0.26) or microscopy negative for both pyuria and bacteriuria (Pooled LR- = 0.11, 95% CI: 0.05, 0.23) can be used to rule out UTI. A test for glucose showed promise in potty-trained children. However, all studies were over 30 years old. Further evaluation of this test may be useful. Conclusion: Dipstick negative for both LE and nitrite or microscopic analysis negative for both pyuria and bacteriuria of a clean voided urine, bag, or nappy/pad specimen may reasonably be used to rule out UTI. These patients can then reasonably be excluded from further investigation, without the need for confirmatory culture. Similarly, combinations of positive tests could be used to rule in UTI, and trigger further investigation
Computational cancer biology: education is a natural key to many locks
BACKGROUND: Oncology is a field that profits tremendously from the genomic data generated by high-throughput technologies, including next-generation sequencing. However, in order to exploit, integrate, visualize and interpret such high-dimensional data efficiently, non-trivial computational and statistical analysis methods are required that need to be developed in a problem-directed manner. DISCUSSION: For this reason, computational cancer biology aims to fill this gap. Unfortunately, computational cancer biology is not yet fully recognized as a coequal field in oncology, leading to a delay in its maturation and, as an immediate consequence, an under-exploration of high-throughput data for translational research. SUMMARY: Here we argue that this imbalance, favoring ’wet lab-based activities’, will be naturally rectified over time, if the next generation of scientists receives an academic education that provides a fair and competent introduction to computational biology and its manifold capabilities. Furthermore, we discuss a number of local educational provisions that can be implemented on university level to help in facilitating the process of harmonization
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