11,432 research outputs found
On the Trace Anomaly and the Anomaly Puzzle in N=1 Pure Yang-Mills
The trace anomaly of the energy-momentum tensor is usually quoted in the form
which is proportional to the beta function of the theory. However, there are in
general many definitions of gauge couplings depending on renormalization
schemes, and hence many beta functions. In particular, N=1 supersymmetric pure
Yang-Mills has the holomorphic gauge coupling whose beta function is one-loop
exact, and the canonical gauge coupling whose beta function is given by the
Novikov-Shifman-Vainshtein-Zakharov beta function. In this paper, we study
which beta function should appear in the trace anomaly in N=1 pure Yang-Mills.
We calculate the trace anomaly by employing the N=4 regularization of N=1 pure
Yang-Mills. It is shown that the trace anomaly is given by one-loop exact form
if the composite operator appearing in the trace anomaly is renormalized in a
preferred way. This result gives the simplest resolution to the anomaly puzzle
in N=1 pure Yang-Mills. The most important point is to examine in which scheme
the quantum action principle is valid, which is crucial in the derivation of
the trace anomaly.Comment: 25 pages, 1 figure; v2:slight correction in sec.5, minor addition in
appendi
Room temperature plasmon laser by total internal reflection
Plasmon lasers create and sustain intense and coherent optical fields below
light's diffraction limit with the unique ability to drastically enhance
light-matter interactions bringing fundamentally new capabilities to
bio-sensing, data storage, photolithography and optical communications.
However, these important applications require room temperature operation, which
remains a major hurdle. Here, we report a room temperature semiconductor
plasmon laser with both strong cavity feedback and optical confinement to
1/20th of the wavelength. The strong feedback arises from total internal
reflection of surface plasmons, while the confinement enhances the spontaneous
emission rate by up to 20 times.Comment: 8 Page, 2 Figure
The role of mutation rate variation and genetic diversity in the architecture of human disease
Background
We have investigated the role that the mutation rate and the structure of genetic variation at a locus play in determining whether a gene is involved in disease. We predict that the mutation rate and its genetic diversity should be higher in genes associated with disease, unless all genes that could cause disease have already been identified.
Results
Consistent with our predictions we find that genes associated with Mendelian and complex disease are substantially longer than non-disease genes. However, we find that both Mendelian and complex disease genes are found in regions of the genome with relatively low mutation rates, as inferred from intron divergence between humans and chimpanzees, and they are predicted to have similar rates of non-synonymous mutation as other genes. Finally, we find that disease genes are in regions of significantly elevated genetic diversity, even when variation in the rate of mutation is controlled for. The effect is small nevertheless.
Conclusions
Our results suggest that gene length contributes to whether a gene is associated with disease. However, the mutation rate and the genetic architecture of the locus appear to play only a minor role in determining whether a gene is associated with disease
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Mycolactone-dependent depletion of endothelial cell thrombomodulin is strongly associated with fibrin deposition in Buruli ulcer lesions
A well-known histopathological feature of diseased skin in Buruli ulcer (BU) is coagulative necrosis caused by the Mycobacterium ulcerans macrolide exotoxin mycolactone. Since the underlying mechanism is not known, we have investigated the effect of mycolactone on endothelial cells, focussing on the expression of surface anticoagulant molecules involved in the protein C anticoagulant pathway. Congenital deficiencies in this natural anticoagulant pathway are known to induce thrombotic complications such as purpura fulimans and spontaneous necrosis. Mycolactone profoundly decreased thrombomodulin (TM) expression on the surface of human dermal microvascular endothelial cells (HDMVEC) at doses as low as 2ng/ml and as early as 8hrs after exposure. TM activates protein C by altering thrombin's substrate specificity, and exposure of HDMVEC to mycolactone for 24 hours resulted in an almost complete loss of the cells' ability to produce activated protein C. Loss of TM was shown to be due to a previously described mechanism involving mycolactone-dependent blockade of Sec61 translocation that results in proteasome-dependent degradation of newly synthesised ER-transiting proteins. Indeed, depletion from cells determined by live-cell imaging of cells stably expressing a recombinant TM-GFP fusion protein occurred at the known turnover rate. In order to determine the relevance of these findings to BU disease, immunohistochemistry of punch biopsies from 40 BU lesions (31 ulcers, nine plaques) was performed. TM abundance was profoundly reduced in the subcutis of 78% of biopsies. Furthermore, it was confirmed that fibrin deposition is a common feature of BU lesions, particularly in the necrotic areas. These findings indicate that there is decreased ability to control thrombin generation in BU skin. Mycolactone's effects on normal endothelial cell function, including its ability to activate the protein C anticoagulant pathway are strongly associated with this. Fibrin-driven tisischemia could contribute to the development of the tissue necrosis seen in BU lesions
Coherent optical wavelength conversion via cavity-optomechanics
We theoretically propose and experimentally demonstrate coherent wavelength
conversion of optical photons using photon-phonon translation in a
cavity-optomechanical system. For an engineered silicon optomechanical crystal
nanocavity supporting a 4 GHz localized phonon mode, optical signals in a 1.5
MHz bandwidth are coherently converted over a 11.2 THz frequency span between
one cavity mode at wavelength 1460 nm and a second cavity mode at 1545 nm with
a 93% internal (2% external) peak efficiency. The thermal and quantum limiting
noise involved in the conversion process is also analyzed, and in terms of an
equivalent photon number signal level are found to correspond to an internal
noise level of only 6 and 4x10-3 quanta, respectively.Comment: 11 pages, 7 figures, appendi
Spectral compression of single photons
Photons are critical to quantum technologies since they can be used for
virtually all quantum information tasks: in quantum metrology, as the
information carrier in photonic quantum computation, as a mediator in hybrid
systems, and to establish long distance networks. The physical characteristics
of photons in these applications differ drastically; spectral bandwidths span
12 orders of magnitude from 50 THz for quantum-optical coherence tomography to
50 Hz for certain quantum memories. Combining these technologies requires
coherent interfaces that reversibly map centre frequencies and bandwidths of
photons to avoid excessive loss. Here we demonstrate bandwidth compression of
single photons by a factor 40 and tunability over a range 70 times that
bandwidth via sum-frequency generation with chirped laser pulses. This
constitutes a time-to-frequency interface for light capable of converting
time-bin to colour entanglement and enables ultrafast timing measurements. It
is a step toward arbitrary waveform generation for single and entangled
photons.Comment: 6 pages (4 figures) + 6 pages (3 figures
Design and rationale of a multi-center, pragmatic, open-label randomized trial of antimicrobial therapy - the study of clinical efficacy of antimicrobial therapy strategy using pragmatic design in Idiopathic Pulmonary Fibrosis (CleanUP-IPF) clinical trial
Compelling data have linked disease progression in patients with idiopathic pulmonary fibrosis (IPF) with lung dysbiosis and the resulting dysregulated local and systemic immune response. Moreover, prior therapeutic trials have suggested improved outcomes in these patients treated with either sulfamethoxazole/ trimethoprim or doxycycline. These trials have been limited by methodological concerns. This trial addresses the primary hypothesis that long-term treatment with antimicrobial therapy increases the time-to-event endpoint of respiratory hospitalization or all-cause mortality compared to usual care treatment in patients with IPF. We invoke numerous innovative features to achieve this goal, including: 1) utilizing a pragmatic randomized trial design; 2) collecting targeted biological samples to allow future exploration of 'personalized' therapy; and 3) developing a strong partnership between the NHLBI, a broad range of investigators, industry, and philanthropic organizations. The trial will randomize approximately 500 individuals in a 1:1 ratio to either antimicrobial therapy or usual care. The site principal investigator will declare their preferred initial antimicrobial treatment strategy (trimethoprim 160 mg/ sulfamethoxazole 800 mg twice a day plus folic acid 5 mg daily or doxycycline 100 mg once daily if body weight is < 50 kg or 100 mg twice daily if ≥50 kg) for the participant prior to randomization. Participants randomized to antimicrobial therapy will receive a voucher to help cover the additional prescription drug costs. Additionally, those participants will have 4-5 scheduled blood draws over the initial 24 months of therapy for safety monitoring. Blood sampling for DNA sequencing and genome wide transcriptomics will be collected before therapy. Blood sampling for transcriptomics and oral and fecal swabs for determination of the microbiome communities will be collected before and after study completion. As a pragmatic study, participants in both treatment arms will have limited in-person visits with the enrolling clinical center. Visits are limited to assessments of lung function and other clinical parameters at time points prior to randomization and at months 12, 24, and 36. All participants will be followed until the study completion for the assessment of clinical endpoints related to hospitalization and mortality events. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT02759120
Separation of Oligosaccharides from Lotus Seeds via Medium-pressure Liquid Chromatography Coupled with ELSD and DAD
peer-reviewedLotus seeds were identified by the Ministry of Public Health of China as both food and medicine. One general function of lotus seeds is to improve intestinal health. However, to date, studies evaluating the relationship between bioactive compounds in lotus seeds and the physiological activity of the intestine are limited. In the present study, by using medium pressure liquid chromatography coupled with evaporative light-scattering detector and diode-array detector, five oligosaccharides were isolated and their structures were further characterized by electrospray ionization-mass spectrometry and gas chromatography-mass spectrometry. In vitro testing determined that LOS3-1 and LOS4 elicited relatively good proliferative effects on Lactobacillus delbrueckii subsp. bulgaricus. These results indicated a structure-function relationship between the physiological activity of oligosaccharides in lotus seeds and the number of probiotics applied, thus providing room for improvement of this particular feature. Intestinal probiotics may potentially become a new effective drug target for the regulation of immunity
Genes Suggest Ancestral Colour Polymorphisms Are Shared across Morphologically Cryptic Species in Arctic Bumblebees
email Suzanne orcd idCopyright: © 2015 Williams et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Accuracy and repeatability of wrist joint angles in boxing using an electromagnetic tracking system
© 2019, The Author(s). The hand-wrist region is reported as the most common injury site in boxing. Boxers are at risk due to the amount of wrist motions when impacting training equipment or their opponents, yet we know relatively little about these motions. This paper describes a new method for quantifying wrist motion in boxing using an electromagnetic tracking system. Surrogate testing procedure utilising a polyamide hand and forearm shape, and in vivo testing procedure utilising 29 elite boxers, were used to assess the accuracy and repeatability of the system. 2D kinematic analysis was used to calculate wrist angles using photogrammetry, whilst the data from the electromagnetic tracking system was processed with visual 3D software. The electromagnetic tracking system agreed with the video-based system (paired t tests) in both the surrogate ( 0.9). In the punch testing, for both repeated jab and hook shots, the electromagnetic tracking system showed good reliability (ICCs > 0.8) and substantial reliability (ICCs > 0.6) for flexion–extension and radial-ulnar deviation angles, respectively. The results indicate that wrist kinematics during punching activities can be measured using an electromagnetic tracking system
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