726 research outputs found
Performance of a Ka-band transponder breadboard for deep-space applications
This article summarizes the design concepts applied in the development of and advanced Ka-band (34.4 GHz/32 GHz) transponder breadboard for the next generation of space communications systems applications. The selected architecture upgrades the X-band (7.2 GHz/8.4 GHz) deep-space transponder (DST) to provide Da-band up/Ka- and X-band down capability. The Ka-band transponder breadboard incorporates several state-of-the-art components, including sampling mixers, a Ka-band dielectric resonator oscillator, and microwave monolithic integrated circuits (MMICs). The MMICs that were tested in the breadboard include upconverters, downconverters, automatic gain control circuits, mixers, phase modulators, and amplifiers. The measured receiver dynamic range, tracking range, acquisition rate, static phase error, and phase jitter characteristics of the Ka-band breadboard interfaced to the advanced engineering model X-band DST are in good agreement with the expected performance. The results show a receiver tracking threshold of -149 dBm with a dynamic range of 80 dB and a downlink phase jitter of 7 deg rms. The analytical results of phase noise and Allan standard deviation are in good agreement with the experimental results
Macroscopic superpositions via nested interferometry: finite temperature and decoherence considerations
Recently there has been much interest in optomechanical devices for the
production of macroscopic quantum states. Here we focus on a proposed scheme
for achieving macroscopic superpositions via nested interferometry. We consider
the effects of finite temperature on the superposition produced. We also
investigate in detail the scheme's feasibility for probing various novel
decoherence mechanisms.Comment: 12 pages, 2 figure
On the decay of deformed actinide nuclei
decay through a deformed potential barrier produces significant
mixing of angular momenta when mapped from the nuclear interior to the outside.
Using experimental branching ratios and either semi-classical or
coupled-channels transmission matrices, we have found that there is a set of
internal amplitudes which are essentially constant for all even--even actinide
nuclei. These same amplitudes also give good results for the known anisotropic
particle emission of the favored decays of odd nuclei in the same mass
region.
PACS numbers: 23.60.+e, 24.10.Eq, 27.90.+bComment: 5 pages, latex (revtex style), 2 embedded postscript figures
uuencoded gz-compressed .tar file To appear in Physical Review Letter
Evolving Identification of Blood Cells Associated with Clinically Isolated Syndrome: Importance of Time since Clinical Presentation and Diagnostic MRI
It is not clear how the profile of immune cells in peripheral blood differs between patients with clinically isolated syndrome (CIS) and healthy controls (HC). This study aimed to identify a CIS peripheral blood signature that may provide clues for potential immunomodulatory approaches early in disease. Peripheral blood mononuclear cells (PBMCs) were collected from 18 people with CIS, 19 HC and 13 individuals with other demyelinating conditions (ODC) including multiple sclerosis (MS). Individuals with CIS separated into two groups, namely those with early (â€14 days post-diagnostic magnetic resonance imaging (MRI); n = 6) and late (â„27 days; n = 12) blood sampling. Transitional B cells were increased in the blood of CIS patients independently of when blood was taken. However, there were two time-dependent effects found in the late CIS group relative to HC, including decreased CD56bright NK cells, which correlated significantly with time since MRI, and increased CD141+ myeloid dendritic cell (mDC2) frequencies. Higher CD1c+ B cells and lower non-classical monocyte frequencies were characteristic of more recent demyelinating disease activity (ODC and early CIS). Analysing cell populations by time since symptoms (subjective) and diagnostic MRI (objective) may contribute to understanding CIS
Identifying Epstein-Barr virus EBNA-1 sequence variation using 454 FLX technology in Multiple Sclerosis patient samples
No abstract availabl
A collinear-spin machine learned interatomic potential for Fe\textsubscript{7}Cr\textsubscript{2}Ni alloy
We have developed a new machine learned interatomic potential for the
prototypical austenitic steel FeCrNi, using the Gaussian
approximation potential (GAP) framework. This new GAP can model the alloy's
properties with higher accuracy than classical interatomic potentials like
embedded atom models (EAM), while also allowing us to collect much more
statistics than expensive first-principles methods like density functional
theory (DFT). We also extended the GAP input descriptors to approximate the
effects of collinear spins (Spin GAP), and demonstrate how this extended model
successfully predicts low temperature structural distortions due to the
antiferromagnetic spin state. We demonstrate the application of the Spin GAP
model for bulk properties and vacancies and validate against DFT. These results
are a step towards modelling ageing in austenitic steels with close to DFT
accuracy but at a fraction of its cost
Multiple Sclerosis Patient Sequence Variation In Epstein-Barr Virus Nuclear Antigen 1
No abstract availabl
Aesthetics and literature : a problematic relation?
The paper argues that there is a proper place for literature within aesthetics but that care must be taken in identifying just what the relation is. In characterising aesthetic pleasure associated with literature it is all too easy to fall into reductive accounts, for example, of literature as merely "fine writing". Belleslettrist or formalistic accounts of literature are rejected, as are two other kinds of reduction, to pure meaning properties and to a kind of narrative realism. The idea is developed that literature-both poetry and prose fiction-invites its own distinctive kind of aesthetic appreciation which far from being at odds with critical practice, in fact chimes well with it
Levinson's Theorem for Non-local Interactions in Two Dimensions
In the light of the Sturm-Liouville theorem, the Levinson theorem for the
Schr\"{o}dinger equation with both local and non-local cylindrically symmetric
potentials is studied. It is proved that the two-dimensional Levinson theorem
holds for the case with both local and non-local cylindrically symmetric cutoff
potentials, which is not necessarily separable. In addition, the problems
related to the positive-energy bound states and the physically redundant state
are also discussed in this paper.Comment: Latex 11 pages, no figure, submitted to J. Phys. A Email:
[email protected], [email protected]
IgG 3 + B cells are associated with the development of multiple sclerosis
Objectives
Diseaseâmodifying therapies (DMTs) targeting B cells are amongst the most effective for preventing multiple sclerosis (MS) progression. IgG3 antibodies and their uncharacterised Bâcell clones are predicted to play a pathogenic role in MS. Identifying subsets of IgG3+ B cells involved in MS progression could improve diagnosis, could inform timely disease intervention and may lead to new DMTs that target B cells more specifically.
Methods
We designed a 31âparameter Bâcellâfocused mass cytometry panel to interrogate the role of peripheral blood IgG3+ B cells in MS progression of two different patient cohorts: one to investigate the Bâcell subsets involved in conversion from clinically isolated syndrome (CIS) to MS; and another to compare MS patients with inactive or active stages of disease. Each independent cohort included a group of nonâMS controls.
Results
Nine distinct CD20+IgDâIgG3+ Bâcell subsets were identified. Significant changes in the proportion of CD21+CD24+CD27âCD38â and CD27+CD38hiCD71hi memory Bâcell subsets correlated with changes in serum IgG3 levels and time to conversion from CIS to MS. The same CD38â doubleânegative Bâcell subset was significantly elevated in MS patients with active forms of the disease. A third CD21+CD24+CD27+CD38â subset was elevated in patients with active MS, whilst narrowband UVB significantly reduced the proportion of this switchedâmemory Bâcell subset.
Conclusion
We have identified previously uncharacterised subsets of IgG3+ B cells and shown them to correlate with autoimmune attacks on the central nervous system (CNS). These results highlight the potential for therapies that specifically target IgG3+ B cells to impact MS progression
- âŠ