774 research outputs found
Collinear and Soft Limits of Multi-Loop Integrands in N=4 Yang-Mills
It has been argued in arXiv:1112.6432 that the planar four-point integrand in
N=4 super Yang-Mills theory is uniquely determined by dual conformal invariance
together with the absence of a double pole in the integrand of the logarithm in
the limit as a loop integration variable becomes collinear with an external
momentum. In this paper we reformulate this condition in a simple way in terms
of the amplitude itself, rather than its logarithm, and verify that it holds
for two- and three-loop MHV integrands for n>4. We investigate the extent to
which this collinear constraint and a constraint on the soft behavior of
integrands can be used to determine integrands. We find an interesting
complementarity whereby the soft constraint becomes stronger while the
collinear constraint becomes weaker at larger n. For certain reasonable choices
of basis at two and three loops the two constraints in unison appear strong
enough to determine MHV integrands uniquely for all n.Comment: 27 pages, 14 figures; v2: very minor change
Dapsone-induced agranulocytosis leading to perianal abscess and death: a case report
<p>Abstract</p> <p>Introduction</p> <p>Dapsone (diaminodiphenylsulfone) is used for the treatment of intractable skin diseases such as pemphigus and leprosy. The side effects of Dapsone are anemia, leukopenia, and liver dysfunction. Here, we present a case of agranulocytosis-induced septic shock, which was a side effect of Dapsone.</p> <p>Case presentation</p> <p>An 82-year-old Japanese woman was transferred to our hospital with fever, leucopenia, and respiratory arrest. At the previous hospital, she had been administered Dapsone for linear IgA bullous dermatosis. At the time of admission, she presented with methemoglobinemia and septic shock, which was due to immunosuppression caused by the normal dose of Dapsone. Although her overall health initially improved, her condition deteriorated because of septic shock caused by an anal fistula. She died of sepsis on hospital day 80.</p> <p>Conclusion</p> <p>One of the side effects of Dapsone is agranulocytosis. Patients with agranulocytosis may be in danger of developing anal fistula. Therefore, care must be taken if a patient with agranulocytosis develops a decubitus ulcer in the sacral region, since it could develop into a fistula-in-ano.</p
Winner-take-all selection in a neural system with delayed feedback
We consider the effects of temporal delay in a neural feedback system with
excitation and inhibition. The topology of our model system reflects the
anatomy of the avian isthmic circuitry, a feedback structure found in all
classes of vertebrates. We show that the system is capable of performing a
`winner-take-all' selection rule for certain combinations of excitatory and
inhibitory feedback. In particular, we show that when the time delays are
sufficiently large a system with local inhibition and global excitation can
function as a `winner-take-all' network and exhibit oscillatory dynamics. We
demonstrate how the origin of the oscillations can be attributed to the finite
delays through a linear stability analysis.Comment: 8 pages, 6 figure
Manipulating infrared photons using plasmons in transparent graphene superlattices
Superlattices are artificial periodic nanostructures which can control the
flow of electrons. Their operation typically relies on the periodic modulation
of the electric potential in the direction of electron wave propagation. Here
we demonstrate transparent graphene superlattices which can manipulate infrared
photons utilizing the collective oscillations of carriers, i.e., plasmons of
the ensemble of multiple graphene layers. The superlattice is formed by
depositing alternating wafer-scale graphene sheets and thin insulating layers,
followed by patterning them all together into 3-dimensional
photonic-crystal-like structures. We demonstrate experimentally that the
collective oscillation of Dirac fermions in such graphene superlattices is
unambiguously nonclassical: compared to doping single layer graphene,
distributing carriers into multiple graphene layers strongly enhances the
plasmonic resonance frequency and magnitude, which is fundamentally different
from that in a conventional semiconductor superlattice. This property allows us
to construct widely tunable far-infrared notch filters with 8.2 dB rejection
ratio and terahertz linear polarizers with 9.5 dB extinction ratio, using a
superlattice with merely five graphene atomic layers. Moreover, an unpatterned
superlattice shields up to 97.5% of the electromagnetic radiations below 1.2
terahertz. This demonstration also opens an avenue for the realization of other
transparent mid- and far-infrared photonic devices such as detectors,
modulators, and 3-dimensional meta-material systems.Comment: under revie
Mellin Amplitudes for Dual Conformal Integrals
Motivated by recent work on the utility of Mellin space for representing
conformal correlators in /CFT, we study its suitability for representing
dual conformal integrals of the type which appear in perturbative scattering
amplitudes in super-Yang-Mills theory. We discuss Feynman-like rules for
writing Mellin amplitudes for a large class of integrals in any dimension, and
find explicit representations for several familiar toy integrals. However we
show that the power of Mellin space is that it provides simple representations
even for fully massive integrals, which except for the single case of the
4-mass box have not yet been computed by any available technology. Mellin space
is also useful for exhibiting differential relations between various multi-loop
integrals, and we show that certain higher-loop integrals may be written as
integral operators acting on the fully massive scalar -gon in
dimensions, whose Mellin amplitude is exactly 1. Our chief example is a very
simple formula expressing the 6-mass double box as a single integral of the
6-mass scalar hexagon in 6 dimensions.Comment: 29+7 page
Fractional quantum Hall effect in a quantum point contact at filling fraction 5/2
Recent theories suggest that the excitations of certain quantum Hall states
may have exotic braiding statistics which could be used to build topological
quantum gates. This has prompted an experimental push to study such states
using confined geometries where the statistics can be tested. We study the
transport properties of quantum point contacts (QPCs) fabricated on a
GaAs/AlGaAs two dimensional electron gas that exhibits well-developed
fractional quantum Hall effect, including at bulk filling fraction 5/2. We find
that a plateau at effective QPC filling factor 5/2 is identifiable in point
contacts with lithographic widths of 1.2 microns and 0.8 microns, but not 0.5
microns. We study the temperature and dc-current-bias dependence of the 5/2
plateau in the QPC, as well as neighboring fractional and integer plateaus in
the QPC while keeping the bulk at filling factor 3. Transport near QPC filling
factor 5/2 is consistent with a picture of chiral Luttinger liquid edge-states
with inter-edge tunneling, suggesting that an incompressible state at 5/2 forms
in this confined geometry
Quantitative assessment of cardiac load-responsiveness during extracorporeal life support: case and rationale
We describe a case of a patient assisted by extracorporeal life support, in which we obtained the dynamic filling index, a measure for venous volume during extracorporeal life support, and used this index to assess cardiac load-responsiveness during acute reloading. While reloading, the obtained findings on cardiac pump function by the dynamic filling index were supported by trans-esophageal echocardiography and standard pressure measurement. This suggests that the dynamic filling index can be used to assess cardiac load-responsiveness during extracorporeal life support
Clinical Characteristics of Anorectal Mycoplasma genitalium Infection and Microbial Cure in Men Who Have Sex With Men.
BACKGROUND: We report clinical characteristics of proctitis caused solely by Mycoplasma genitalium (MG) compared with chlamydia and gonococcus. We determined the proportions cured with first-line (azithromycin) and second-line antimicrobials (moxifloxacin, pristinamycin). METHODS: A total of 166 patients attending Melbourne Sexual Health Centre from 2012 to 2016 with symptoms of proctitis were tested for MG, Chlamydia trachomatis, and Neisseria gonorrhoeae. Demographic characteristics, sexual behaviors, clinical symptoms, and signs were recorded. Multinomial multivariable logistic regression was used to test for significant differences in symptoms and signs for the pathogens detected. RESULTS: Seventeen percent of men had MG (95% confidence interval, 12-24), 21% had chlamydia (15-27), and 40% had gonococcal monoinfection (32-48), whereas 22% had MG coinfection (16-29). Relative to men with MG monoinfection, those with chlamydial monoinfection reported more anal pain (adjusted prevalence odds ratio (aPOR), 4.68 [1.41-14.19]), whereas men with gonococcal monoinfection reported more anal pain (aPOR, 6.75 [2.21-20.55]) and tenesmus (aPOR, 15.44 [1.62-146.90]), but less anal itch (aPOR, 0.32 [0.11-0.93]). The microbiological cure for MG using azithromycin was low at 35% (22-50), whereas moxifloxacin subsequently cured 92% (64-100) and pristinamycin cured 79% (54-94) of infections. CONCLUSIONS: M. genitalium was almost as common as chlamydia in men presenting to a sexual health center with symptoms of proctitis. Men with anorectal MG monoinfection were less likely to have symptoms and signs compared with those with chlamydia or gonococcus monoinfection. Cure for men with symptomatic anorectal MG by azithromycin was low. We suggest routine testing for MG in cases of proctitis, with test of cure after treatment being essential
Phrase Frequency Effects in Language Production
A classic debate in the psychology of language concerns the question of the grain-size of the linguistic information that is stored in memory. One view is that only morphologically simple forms are stored (e.g., ‘car’, ‘red’), and that more complex forms of language such as multi-word phrases (e.g., ‘red car’) are generated on-line from the simple forms. In two experiments we tested this view. In Experiment 1, participants produced noun+adjective and noun+noun phrases that were elicited by experimental displays consisting of colored line drawings and two superimposed line drawings. In Experiment 2, participants produced noun+adjective and determiner+noun+adjective utterances elicited by colored line drawings. In both experiments, naming latencies decreased with increasing frequency of the multi-word phrase, and were unaffected by the frequency of the object name in the utterance. These results suggest that the language system is sensitive to the distribution of linguistic information at grain-sizes beyond individual words
- …