33,196 research outputs found
Surface Operators in N=2 Abelian Gauge Theory
We generalise the analysis in [arXiv:0904.1744] to superspace, and explicitly
prove that for any embedding of surface operators in a general, twisted N=2
pure abelian theory on an arbitrary four-manifold, the parameters transform
naturally under the SL(2,Z) duality of the theory. However, for
nontrivially-embedded surface operators, exact S-duality holds if and only if
the "quantum" parameter effectively vanishes, while the overall SL(2,Z) duality
holds up to a c-number at most, regardless. Nevertheless, this observation sets
the stage for a physical proof of a remarkable mathematical result by
Kronheimer and Mrowka--that expresses a "ramified" analog of the Donaldson
invariants solely in terms of the ordinary Donaldson invariants--which, will
appear, among other things, in forthcoming work. As a prelude to that, the
effective interaction on the corresponding u-plane will be computed. In
addition, the dependence on second Stiefel-Whitney classes and the appearance
of a Spin^c structure in the associated low-energy Seiberg-Witten theory with
surface operators, will also be demonstrated. In the process, we will stumble
upon an interesting phase factor that is otherwise absent in the "unramified"
case.Comment: 46 pages. Minor refinemen
On the age of the magnetically active WW Psa and TX Psa members of the beta Pictoris association
There are a variety of different techniques available to estimate the ages of
pre-main-sequence stars. Components of physical pairs, thanks to their strict
coevality and the mass difference, such as the binary system analysed in this
paper, are best suited to test the effectiveness of these different techniques.
We consider the system WW Psa + TX Psa whose membership of the 25-Myr beta
Pictoris association has been well established by earlier works. We investigate
which age dating technique provides the best agreement between the age of the
system and that of the association. We have photometrically monitored WW Psa
and TX Psa and measured their rotation periods as P = 2.37d and P = 1.086d,
respectively. We have retrieved from the literature their Li equivalent widths
and measured their effective temperatures and luminosities. We investigate
whether the ages of these stars derived using three independent techniques are
consistent with the age of the beta Pictoris association. We find that the
rotation periods and the Li contents of both stars are consistent with the
distribution of other bona fide members of the cluster. On the contrary, the
isochronal fitting provides similar ages for both stars, but a factor of about
four younger than the quoted age of the association, or about 30% younger when
the effects of magnetic fields are included. We explore the origin of the
discrepant age inferred from isochronal fitting, including the possibilities
that either the two components may be unresolved binaries or that the basic
stellar parameters of both components are altered by enhanced magnetic
activity. The latter is found to be the more reasonable cause, suggesting that
age estimates based on the Li content is more reliable than isochronal fitting
for pre-main-sequence stars with pronounced magnetic activity.Comment: Accepted by Astronomy and Astrophysics on December 13, 2016. 13 pages
and 11 figure
Diversity, Distribution and Biological Activity of Soft Corals (Octocorallia, Alcyonacea) in Singapore
The Southern Islands of Singapore are known to contain coral reefs which are high in biodiversity. However, the diversity of soft corals had received little attention to date. This study was conducted to determine the soft coral diversity in Singapore reefs as well as to conduct preliminary bioactivity tests on the organic extracts from these soft corals. A 100-meter line transect was used to survey soft corals at a 3m depth at ten different sample sites. Sclerites from samples were used to identify the soft corals to the generic level. This study uncovered the following genera of soft corals: Carijoa spp., Cladiella spp., Sinularia spp., Lobophytum spp., Sarcophyton spp., Stereonephthya spp., and Nephthea spp. In addition, an unidentified genus of soft coral was observed at Kusu Island. Cladiella spp. yielded the highest number of colonies, and Sarcophyton spp. had the highest coverage in terms of total colony diameter. The brine shrimp (Artemia salina) toxicity assay was carried out to screen for toxicity of the soft coral extracts at concentrations of 10, 100, and 1000 ppm. Results showed high levels of toxicity in extracts of Sarcophyton spp. and Cladiella spp., indicating that these soft corals are potentially good sources of bioactive compounds for drug discovery
Pengaruh Pembangunan Infrastruktur Terhadap Pengembangan Sektor Pertanian Di Kabupaten Muaro Jambi
This Research aim a) To analyse infrastructure growth to, market draught irrigation Muaro Jambi Regency Period 2000-2010; b) To analyse infrastructure expense allocation growth and its proportion to totalizeing area expense Muaro Jambi Regency Period 2000-2010 c) To know and analyse ready influence infrastructure, market and irrigation to agricultural sector added value Muaro Jambi Regency Period 2000-2010. Result of research indicate that a) During period 2000-2010 infrastructure growth rate in Muaro Jambi Regency is equal to 6,60 percent per year, in same period infrastructure growth rate irrigation in Muaro Jambi Regency equal to 15,70 percent and infrastructure growth natural market growth mean equal to 18,16 percent b) meanly during period 2000-2010 infrastructure expense proportion to area expense equal to 39,85 percent, with growth per year mean equal to 65,32 percent meanly during period 2000-2010 growth agricultural sector added value Muaro Jambi Regency equal to 4,75 percent c) Infrastructure variable street, market and irrigation by together have an effect on positive and signifikan to velue added agricultural sector. By parsial infrastructure variable irrigation and street have an effect on by signifikan to agricultural sector added value, but market variable though have an effect on positive but don't signifikan
Effects of rapid thermal annealing on device characteristics of InGaAs/GaAs quantum dot infrared photodetectors
In this work, rapid thermal annealing was performed on InGaAs/GaAs quantum dot infrared photodetectors (QDIPs) at different temperatures. The photoluminescence showed a blueshifted spectrum in comparison with the as-grown sample when the annealing temperature was higher than 700 °C, as a result of thermal interdiffusion of the quantum dots (QDs). Correspondingly, the spectral response from the annealed QDIP exhibited a redshift. At the higher annealing temperature of 800 °C, in addition to the largely redshifted photoresponse peak of 7.4 µm (compared with the 6.1 µm of the as-grown QDIP), a high energy peak at 5.6 µm (220 meV) was also observed, leading to a broad spectrum linewidth of 40%. This is due to the large interdiffusion effect which could greatly vary the composition of the QDs and thus increase the relative optical absorption intensity at higher energy. The other important detector characteristics such as dark current, peak responsivity, and detectivity were also measured. It was found that the overall device performance was not affected by low annealing temperature, however, for high annealing temperature, some degradation in device detectivity (but not responsivity) was observed. This is a consequence of increased dark current due to defect formation and increased ground state energy. © 2006 American Institute of Physic
Functional outcomes following ileal pouch-anal anastomosis (IPAA) in older patients: a systematic review
Aim Ileal pouch-anal anastomosis (IPAA) is performed in ulcerative colitis or familial adenomatous polyposis with a view to restoration of GI continuity and prevention of permanent faecal diversion. Debate exists as to its safety in older patients. This review aims to assess functional outcomes and safety of restorative proctocolectomy (RPC) in older compared to younger patients. Methods Literature search was performed for age-stratified studies which assessed functional outcomes of IPAA. Twelve papers were included overall. Patients were categorized into ‘older’ and ‘younger’ groups. Analysis was split into three separate parts: 1. Age cut-off of 50 ± 5 years (with sensitivity analysis); 2. Age cut-off of 65 ± years; 3. Long-term outcomes (>10 years). Results With an age cut-off of 50 years (4327 versus 513 patients), complication rates were comparable with the exception of an increased rate of small-bowel obstruction in the younger patients (p = 0.034). At 1 year, 24-h stool frequency was significantly higher in the older patient group (p < 0.0001). Daytime (p < 0.0001) and night-time (p < 0.0001) incontinence rates were also significantly higher in older patients. Overall, function deteriorated with time across all ages; however, after 10 years, there was no significant difference in incontinence rates between age groups. Dehydration and electrolyte loss was a significant problem in patients over 65 (p < 0.0001). Despite differences in postoperative function, quality of life was comparable between groups; however, only a few studies reported quality of life data. Conclusion IPAA is safe in older patients, although treating clinicians should bear in mind the increased risk of dehydration. Postoperative function is worse in older patients, but seems to level out with time and does not appear to significantly impact on overall quality of life and patient satisfaction. Assessment for suitability for RPC should not be based on chronological age in isolation. It is imperative that the correct support is given to older patients with worsened postoperative function in order to maintain patient satisfaction and adequate quality of life
Nanoscale broadband transmission lines for spin qubit control
The intense interest in spin-based quantum information processing has caused
an increasing overlap between two traditionally distinct disciplines, such as
magnetic resonance and nanotechnology. In this work we discuss rigourous design
guidelines to integrate microwave circuits with charge-sensitive
nanostructures, and describe how to simulate such structures accurately and
efficiently. We present a new design for an on-chip, broadband, nanoscale
microwave line that optimizes the magnetic field driving a spin qubit, while
minimizing the disturbance on a nearby charge sensor. This new structure was
successfully employed in a single-spin qubit experiment, and shows that the
simulations accurately predict the magnetic field values even at frequencies as
high as 30 GHz.Comment: 18 pages, 8 figures, 1 table, pdflate
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