207 research outputs found
Electromagnetic wormholes via handlebody constructions
Cloaking devices are prescriptions of electrostatic, optical or
electromagnetic parameter fields (conductivity , index of refraction
, or electric permittivity and magnetic permeability
) which are piecewise smooth on and singular on a
hypersurface , and such that objects in the region enclosed by
are not detectable to external observation by waves. Here, we give related
constructions of invisible tunnels, which allow electromagnetic waves to pass
between possibly distant points, but with only the ends of the tunnels visible
to electromagnetic imaging. Effectively, these change the topology of space
with respect to solutions of Maxwell's equations, corresponding to attaching a
handlebody to . The resulting devices thus function as
electromagnetic wormholes.Comment: 25 pages, 6 figures (some color
Diversity Characterization of Optimized Two-Antenna Systems for UMTS Handsets
This paper presents the evaluation of the diversity performance of several two-antenna systems for UMTS terminals. All the measurements are done in a reverberation chamber and in a Wheeler cap setup. First, a two-antenna system having poor isolation between its radiators is measured. Then, the performance of this structure is compared with two optimized structures having high isolation and high total efficiency, thanks to the implementation of a neutralization technique between the radiating elements. The key diversity parameters of all these systems are discussed, that is, the total efficiency of the antenna, the envelope correlation coefficient, the diversity gains, the mean effective gain (MEG), and the MEG ratio. The comparison of all these results is especially showing the benefit brought back by the neutralization technique
Design of Electromagnetic Cloaks and Concentrators Using Form-Invariant Coordinate Transformations of Maxwell's Equations
The technique of applying form-invariant, spatial coordinate transformations
of Maxwell's equations can facilitate the design of structures with unique
electromagnetic or optical functionality. Here, we illustrate the
transformation-optical approach in the designs of a square electromagnetic
cloak and an omni-directional electromagnetic field concentrator. The
transformation equations are described and the functionality of the devices is
numerically confirmed by two-dimensional finite element simulations. The two
devices presented demonstrate that the transformation optic approach leads to
the specification of complex, anisotropic and inhomogeneous materials with well
directed and distinct electromagnetic behavior.Comment: submitted to "Photonics and Nanostructures", Special Issue "PECS
VII", Elsevie
ACBAR: The Arcminute Cosmology Bolometer Array Receiver
We describe the Arcminute Cosmology Bolometer Array Receiver (ACBAR); a
multifrequency millimeter-wave receiver designed for observations of the Cosmic
Microwave Background (CMB) and the Sunyaev-Zel'dovich effect in clusters of
galaxies. The ACBAR focal plane consists of a 16-pixel, background-limited, 240
mK bolometer array that can be configured to observe simultaneously at 150,
220, 280, and 350 GHz. With 4-5' FWHM Gaussian beam sizes and a 3 degree
azimuth chop, ACBAR is sensitive to a wide range of angular scales. ACBAR was
installed on the 2 m Viper telescope at the South Pole in January 2001. We
describe the design of the instrument and its performance during the 2001 and
2002 observing seasons.Comment: 59 pages, 16 figures -- updated to reflect version published in ApJ
Full-wave invisibility of active devices at all frequencies
There has recently been considerable interest in the possibility, both
theoretical and practical, of invisibility (or "cloaking") from observation by
electromagnetic (EM) waves. Here, we prove invisibility, with respect to
solutions of the Helmholtz and Maxwell's equations, for several constructions
of cloaking devices. Previous results have either been on the level of ray
tracing [Le,PSS] or at zero frequency [GLU2,GLU3], but recent numerical [CPSSP]
and experimental [SMJCPSS] work has provided evidence for invisibility at
frequency . We give two basic constructions for cloaking a region
contained in a domain from measurements of Cauchy data of waves at \p
\Omega; we pay particular attention to cloaking not just a passive object, but
an active device within , interpreted as a collection of sources and sinks
or an internal current.Comment: Final revision; to appear in Commun. in Math. Physic
Tissue microarray analysis of human FRAT1 expression and its correlation with the subcellular localisation of ?-catenin in ovarian tumours
The mechanisms involved in the pathogenesis of ovarian cancer are poorly understood, but evidence suggests that aberrant activation of Wnt/?-catenin signalling pathway plays a significant role in this malignancy. However, the molecular defects that contribute to the activation of this pathway have not been elucidated. Frequently rearranged in advanced T-cell lymphomas-1 (FRAT1) is a candidate for the regulation of cytoplasmic ?-catenin. In this study, we developed in situ hybridisation probes to evaluate the presence of FRAT1 and used an anti-?-catenin antibody to evaluate by immunohistochemistry the expression levels and subcellular localisation of ?-catenin in ovarian cancer tissue microarrays. Expression of FRAT1 was found in some human normal tissues and 47% of ovarian adenocarcinomas. A total of 46% of ovarian serous adenocarcinomas were positive for FRAT1 expression. Accumulation of ?-catenin in the nucleus and/or cytoplasm was observed in 55% ovarian adenocarcinomas and in 59% of serous adenocarcinomas. A significant association was observed in ovarian serous adenocarcinomas between FRAT1 and ?-catenin expression (P<0.01). These findings support that Wnt/?-catenin signalling may be aberrantly activated through FRAT1 overexpression in ovarian serous adenocarcinomas. The mechanism behind the overexpression of FRAT1 in ovarian serous adenocarcinomas and its significance is yet to be investigated
Expression profiling identifies genes involved in neoplastic transformation of serous ovarian cancer
Background: The malignant potential of serous ovarian tumors, the most common ovarian tumor subtype, varies from benign to low malignant potential (LMP) tumors to frankly invasive cancers. Given the uncertainty about the relationship between these different forms, we compared their patterns of gene expression. Methods: Expression profiling was carried out on samples of 7 benign, 7 LMP and 28 invasive (moderate and poorly differentiated) serous tumors and four whole normal ovaries using oligonucleotide microarrays representing over 21,000 genes. Results: We identified 311 transcripts that distinguished invasive from benign tumors, and 20 transcripts that were significantly differentially expressed between invasive and LMP tumors at p < 0.01 (with multiple testing correction). Five genes that were differentially expressed between invasive and either benign or normal tissues were validated by real time PCR in an independent panel of 46 serous tumors (4 benign, 7 LMP, 35 invasive). Overexpression of SLPI and WNT7A and down-regulation of C6orf31, PDGFRA and GLTSCR2 were measured in invasive and LMP compared with benign and normal tissues. Over-expression of WNT7A in an ovarian cancer cell line led to increased migration and invasive capacity. Conclusion: These results highlight several genes that may play an important role across the spectrum of serous ovarian tumorigenesis
Efficacy and safety of baricitinib in hospitalized adults with severe or critical COVID‑19 (Bari‑SolidAct): a randomised, double‑blind, placebo‑controlled phase 3 trial
Background Baricitinib has shown efcacy in hospitalized patients with COVID-19, but no placebo-controlled trials
have focused specifcally on severe/critical COVID, including vaccinated participants.
Methods Bari-SolidAct is a phase-3, multicentre, randomised, double-blind, placebo-controlled trial, enrolling
participants from June 3, 2021 to March 7, 2022, stopped prematurely for external evidence. Patients with severe/
critical COVID-19 were randomised to Baricitinib 4 mg once daily or placebo, added to standard of care. The primary
endpoint was all-cause mortality within 60 days. Participants were remotely followed to day 90 for safety and patient
related outcome measures.
Results Two hundred ninety-nine patients were screened, 284 randomised, and 275 received study drug or placebo
and were included in the modifed intent-to-treat analyses (139 receiving baricitinib and 136 placebo). Median age was 60 (IQR 49–69) years, 77% were male and 35% had received at least one dose of SARS-CoV2 vaccine. There were
21 deaths at day 60 in each group, 15.1% in the baricitinib group and 15.4% in the placebo group (adjusted absolute
diference and 95% CI −0.1% [−8·3 to 8·0]). In sensitivity analysis censoring observations after drug discontinuation
or rescue therapy (tocilizumab/increased steroid dose), proportions of death were 5.8% versus 8.8% (−3.2% [−9.0 to
2.7]), respectively. There were 148 serious adverse events in 46 participants (33.1%) receiving baricitinib and 155 in 51
participants (37.5%) receiving placebo. In subgroup analyses, there was a potential interaction between vaccination
status and treatment allocation on 60-day mortality. In a subsequent post hoc analysis there was a signifcant interac‑
tion between vaccination status and treatment allocation on the occurrence of serious adverse events, with more
respiratory complications and severe infections in vaccinated participants treated with baricitinib. Vaccinated partici‑
pants were on average 11 years older, with more comorbidities.
Conclusion This clinical trial was prematurely stopped for external evidence and therefore underpowered to con‑
clude on a potential survival beneft of baricitinib in severe/critical COVID-19. We observed a possible safety signal in
vaccinated participants, who were older with more comorbidities. Although based on a post-hoc analysis, these fnd‑
ings warrant further investigation in other trials and real-world studies
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