480 research outputs found
Bi-local Construction of Sp(2N)/dS Higher Spin Correspondence
We derive a collective field theory of the singlet sector of the Sp(2N) sigma
model. Interestingly the hamiltonian for the bilocal collective field is the
same as that of the O(N) model. However, the large-N saddle points of the two
models differ by a sign. This leads to a fluctuation hamiltonian with a
negative quadratic term and alternating signs in the nonlinear terms which
correctly reproduces the correlation functions of the singlet sector. Assuming
the validity of the connection between O(N) collective fields and higher spin
fields in AdS, we argue that a natural interpretation of this theory is by a
double analytic continuation, leading to the dS/CFT correspondence proposed by
Anninos, Hartman and Strominger. The bi-local construction gives a map into the
bulk of de Sitter space-time. Its geometric pseudospin-representation provides
a framework for quantization and definition of the Hilbert space. We argue that
this is consistent with finite N grassmanian constraints, establishing the
bi-local representation as a nonperturbative framework for quantization of
Higher Spin Gravity in de Sitter space.Comment: 1 figur
Probe Branes, Time-dependent Couplings and Thermalization in AdS/CFT
We present holographic descriptions of thermalization in conformal field
theories using probe D-branes in AdS X S space-times. We find that the induced
metrics on Dp-brane worldvolumes which are rotating in an internal sphere
direction have horizons with characteristic Hawking temperatures even if there
is no black hole in the bulk AdS. The AdS/CFT correspondence applied to such
systems indeed reveals thermal properties such as Brownian motions and AC
conductivities in the dual conformal field theories. We also use this framework
to holographically analyze time-dependent systems undergoing a quantum quench,
where parameters in quantum field theories, such as a mass or a coupling
constant, are suddenly changed. We confirm that this leads to thermal behavior
by demonstrating the formation of apparent horizons in the induced metric after
a certain time.Comment: LaTeX, 47 pages, 14 figures; Typos corrected and references added
(v2); minor corrections, references added(v3
Hybrid endoscopic thymectomy : combined transesophageal and transthoracic approach in a survival porcine model with cadaver assessment
BACKGROUND:
Video-assisted thoracoscopic surgery thymectomy has been used in the treatment of Myastenia Gravis and thymomas (coexisting or not). In natural orifice transluminal endoscopic surgery, new approaches to the thorax are emerging as alternatives to the classic transthoracic endoscopic surgery. The aim of this study was to assess the feasibility and reliability of hybrid endoscopic thymectomy (HET) using a combined transthoracic and transesophageal approach.
METHODS:
Twelve consecutive in vivo experiments were undertaken in the porcine model (4 acute and 8 survival). The same procedure was assessed in a human cadaver afterward. For HET, an 11-mm trocar was inserted in the 2nd intercostal space in the left anterior axillary line. A 0° 10-mm thoracoscope with a 5-mm working channel was introduced. Transesophageal access was created through a submucosal tunnel using a flexible gastroscope with a single working channel introduced through the mouth. Using both flexible (gastroscope) and rigid (thoracoscope) instruments, the mediastinum was opened; the thymus was dissected, and the vessels were ligated using electrocautery alone.
RESULTS:
Submucosal tunnel creation and esophagotomy were performed safely without incidents in all animals. Complete thymectomy was achieved in all experiments. All animals in the survival group lived for 14 days. Thoracoscopic and postmortem examination revealed pleural adhesions on site of the surgical procedure with no signs of infection. Histological analysis of the proximal third of the esophagus revealed complete cicatrization of both mucosal defect and myotomy site. In the human cadaver, we were able to replicate all the procedure even though we were not able to identify the thymus.
CONCLUSIONS:
Hybrid endoscopic thymectomy is feasible and reliable. HET could be regarded as a possible alternative to classic thoracoscopic approach for patients requiring thymectomy.This project was funded by the FCT Grants project PTDC/SAU-OSM/105578/2008
Parasympathetic nervous system dysfunction, as identified by pupil light reflex, and its possible connection to hearing impairment
Context
Although the pupil light reflex has been widely used as a clinical diagnostic tool for autonomic nervous system dysfunction, there is no systematic review available to summarize the evidence that the pupil light reflex is a sensitive method to detect parasympathetic dysfunction. Meanwhile, the relationship between parasympathetic functioning and hearing impairment is relatively unknown.
Objectives
To 1) review the evidence for the pupil light reflex being a sensitive method to evaluate parasympathetic dysfunction, 2) review the evidence relating hearing impairment and parasympathetic activity and 3) seek evidence of possible connections between hearing impairment and the pupil light reflex.
Methods
Literature searches were performed in five electronic databases. All selected articles were categorized into three sections: pupil light reflex and parasympathetic dysfunction, hearing impairment and parasympathetic activity, pupil light reflex and hearing impairment.
Results
Thirty-eight articles were included in this review. Among them, 36 articles addressed the pupil light reflex and parasympathetic dysfunction. We summarized the information in these data according to different types of parasympathetic-related diseases. Most of the studies showed a difference on at least one pupil light reflex parameter between patients and healthy controls. Two articles discussed the relationship between hearing impairment and parasympathetic activity. Both studies reported a reduced parasympathetic activity in the hearing impaired groups. The searches identified no results for pupil light reflex and hearing impairment.
Discussion and Conclusions
As the first systematic review of the evidence, our findings suggest that the pupil light reflex is a sensitive tool to assess the presence of parasympathetic dysfunction. Maximum constriction velocity and relative constriction amplitude appear to be the most sensitive parameters. There are only two studies investigating the relationship between parasympathetic activity and hearing impairment, hence further research is needed. The pupil light reflex could be a candidate measurement tool to achieve this goal
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Vaccination of Infants with Meningococcal Group B Vaccine (4CMenB) in England.
BACKGROUND: In September 2015, the United Kingdom introduced the multicomponent meningococcal group B vaccine (4CMenB, Bexsero) into its publicly funded national immunization program at a reduced two-dose priming schedule for infants, with a 12-month booster. METHODS: Using data from enhanced national surveillance of invasive meningococcal disease in England, we evaluated the effect of vaccination on the incidence of meningococcal group B disease during the first 3 years of the program. The effect of vaccination was assessed by comparing the observed incidence of disease with the expected incidence based on the incidence during the 4-year prevaccination period in equivalent cohorts and with the use of disease trends in cohorts of children younger than 5 years of age who were not eligible to receive the vaccine. Vaccine effectiveness was estimated with the use of the indirect screening method. RESULTS: 4CMenB uptake in England remained consistently high; data from the first 3 months of 2018 showed that 92.5% of children had completed the primary immunizations by their first birthday and 87.9% had received all three doses by 2 years. From September 2015 through August 2018, the incidence of meningococcal group B disease in England (average annual birth cohort, approximately 650,000 infants) was significantly lower in vaccine-eligible cohorts than the expected incidence (63 observed cases as compared with 253 expected cases; incidence rate ratio, 0.25; 95% confidence interval [CI], 0.19 to 0.36), with a 75% reduction in age groups that were fully eligible for vaccination. The adjusted vaccine effectiveness against meningococcal group B disease was 52.7% (95% CI, -33.5 to 83.2) with a two-dose priming schedule for infants and 59.1% (95% CI, -31.1 to 87.2) with a two-dose priming schedule plus a booster at 1 year). Over the 3-year period, there were 169 cases of meningococcal group B disease in the vaccine-eligible cohorts, and an estimated 277 cases (95% CI, 236 to 323) were prevented. CONCLUSIONS: The 4CMenB program was associated with continued positive effect against meningococcal group B disease in children in England, and protection after three doses of the vaccine was sustained for at least 2 years. (Funded by Public Health England.)
Is the inflammasome a potential therapeutic target in renal disease?
The inflammasome is a large, multiprotein complex that drives proinflammatory cytokine production in response to infection and tissue injury. Pattern recognition receptors that are either membrane bound or cytoplasmic trigger inflammasome assembly. These receptors sense danger signals including damage-associated molecular patterns and pathogen-associated molecular patterns (DAMPS and PAMPS respectively). The best-characterized inflammasome is the NLRP3 inflammasome. On assembly of the NLRP3 inflammasome, post-translational processing and secretion of pro-inflammatory cytokines IL-1β and IL-18 occurs; in addition, cell death may be mediated via caspase-1. Intrinsic renal cells express components of the inflammasome pathway. This is most prominent in tubular epithelial cells and, to a lesser degree, in glomeruli. Several primary renal diseases and systemic diseases affecting the kidney are associated with NLRP3 inflammasome/IL-1β/IL-18 axis activation. Most of the disorders studied have been acute inflammatory diseases. The disease spectrum includes ureteric obstruction, ischaemia reperfusion injury, glomerulonephritis, sepsis, hypoxia, glycerol-induced renal failure, and crystal nephropathy. In addition to mediating renal disease, the IL-1/ IL-18 axis may also be responsible for development of CKD itself and its related complications, including vascular calcification and sepsis. Experimental models using genetic deletions and/or receptor antagonists/antiserum against the NLRP3 inflammasome pathway have shown decreased severity of disease. As such, the inflammasome is an attractive potential therapeutic target in a variety of renal diseases
Collaborative planning approach to inform the implementation of a healthcare manager intervention for hispanics with serious mental illness: a study protocol
Background: This study describes a collaborative planning approach that blends principles of community-based participatory research (CBPR) and intervention mapping to modify a healthcare manager intervention to a new patient population and provider group and to assess the feasibility and acceptability of this modified intervention to improve the physical health of Hispanics with serious mental illness (SMI) and at risk for cardiovascular disease (CVD). Methods: The proposed study uses a multiphase approach that applies CBPR principles and intervention-mapping steps--an intervention-planning approach--to move from intervention planning to pilot testing. In phase I, a community advisory board composed of researchers and stakeholders will be assembled to learn and review the intervention and make initial modifications. Phase II uses a combination of qualitative methods--patient focus groups and stakeholder interviews--to ensure that the modifications are acceptable to all stakeholders. Phase III uses results from phase II to further modify the intervention, develop an implementation plan, and train two care managers on the modified intervention. Phase IV consists of a 12-month open pilot study (N = 30) to assess the feasibility and acceptability of the modified intervention and explore its initial effects. Lastly, phase V consists of analysis of pilot study data and preparation for future funding to develop a more rigorous evaluation of the modified intervention. Discussion: The proposed study is one of the few projects to date to focus on improving the physical health of Hispanics with SMI and at risk for CVD by using a collaborative planning approach to enhance the transportability and use of a promising healthcare manager intervention. This study illustrates how blending health-disparities research and implementation science can help reduce the disproportionate burden of medical illness in a vulnerable population
Do salivary bypass tubes lower the incidence of pharyngocutaneous fistula following total laryngectomy? A retrospective analysis of predictive factors using multivariate analysis
Salivary bypass tubes (SBT) are increasingly used to prevent pharyngocutaneous fistula (PCF) following laryngectomy and pharyngolaryngectomy. There is minimal evidence as to their efficacy and literature is limited. The aim of the study was to determine if SBT prevent PCF. The study was a multicentre retrospective case control series (level of evidence 3b). Patients who underwent laryngectomy or pharyngolaryngectomy for cancer or following cancer treatment between 2011 and 2014 were included in the study. The primary outcome was development of a PCF. Other variables recorded were age, sex, prior radiotherapy or chemoradiotherapy, prior tracheostomy, type of procedure, concurrent neck dissection, use of flap reconstruction, use of prophylactic antibiotics, the suture material used for the anastomosis, tumour T stage, histological margins, day one post-operative haemoglobin and whether a salivary bypass tube was used. Univariate and multivariate analysis were performed. A total of 199 patients were included and 24 received salivary bypass tubes. Fistula rates were 8.3% in the SBT group (2/24) and 24.6% in the control group (43/175). This was not statistically significant on univariate (p value 0.115) or multivariate analysis (p value 0.076). In addition, no other co-variables were found to be significant. No group has proven a benefit of salivary bypass tubes on multivariate analysis. The study was limited by a small case group, variations in tube duration and subjects given a tube may have been identified as high risk of fistula. Further prospective studies are warranted prior to recommendation of salivary bypass tubes following laryngectomy
Obesity-Related Oxidative Stress: the Impact of Physical Activity and Diet Manipulation
Obesity-related oxidative stress, the imbalance between pro-oxidants and antioxidants (e.g., nitric oxide), has been linked to metabolic and cardiovascular disease, including endothelial dysfunction and atherosclerosis. Reactive oxygen species (ROS) are essential for physiological functions including gene expression, cellular growth, infection defense, and modulating endothelial function. However, elevated ROS and/or diminished antioxidant capacity leading to oxidative stress can lead to dysfunction. Physical activity also results in an acute state of oxidative stress. However, it is likely that chronic physical activity provides a stimulus for favorable oxidative adaptations and enhanced physiological performance and physical health, although distinct responses between aerobic and anaerobic activities warrant further investigation. Studies support the benefits of dietary modification as well as exercise interventions in alleviating oxidative stress susceptibility. Since obese individuals tend to demonstrate elevated markers of oxidative stress, the implications for this population are significant. Therefore, in this review our aim is to discuss (i) the role of oxidative stress and inflammation as associated with obesity-related diseases, (ii) the potential concerns and benefits of exercise-mediated oxidative stress, and (iii) the advantageous role of dietary modification, including acute or chronic caloric restriction and vitamin D supplementation
Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe
We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median ). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July
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