416 research outputs found
On Integrable Backgrounds Self-dual under Fermionic T-duality
We study the fermionic T-duality symmetry of integrable Green-Schwarz
sigma-models on AdS backgrounds with Ramond-Ramond fluxes in various
dimensions. We show that sigma-models based on supercosets of PSU supergroups,
such as AdS_2 \times S^2 and AdS_3 \times S^3 are self-dual under fermionic
T-duality, while supercosets of OSp supergroups such as non-critical AdS_2 and
AdS_4 models, and the critical AdS_4 \times CP^3 background are not. We present
a general algebraic argument to when a supercoset is expected to have a
fermionic T-duality symmetry, and when it will fail to have one.Comment: LaTeX, 27 pages, no figures, JHEP3 style; v2: references added; v3: a
comment in subsection 3.3 and a reference added; v4: fixed typos, published
versio
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Deciphering molecular circuits from genetic variation underlying transcriptional responsiveness to stimuli
Individual genetic variation affects gene expression in response to stimuli, often by influencing complex molecular circuits. Here we combine genomic and intermediate-scale transcriptional profiling with computational methods to identify variants that affect the responsiveness of genes to stimuli (responsiveness QTLs; reQTLs) and to position these variants in molecular circuit diagrams. We apply this approach to study variation in transcriptional responsiveness to pathogen components in dendritic cells from recombinant inbred mouse strains. We identify reQTLs that correlate with particular stimuli and position them in known pathways. For example, in response to a virus-like stimulus, a trans-acting variant acts as an activator of the antiviral response; using RNAi, we identify Rgs16 as the likely causal gene. Our approach charts an experimental and analytic path to decipher the mechanisms underlying genetic variation in circuits that control responses to stimuli
On the fermionic T-duality of the AdS_4 \times CP^3 sigma-model
In this note we consider a fermionic T-duality of the coset realization of
the type IIA sigma-model on AdS_4 \times CP^3 with respect to the three flat
directions in AdS_4, six of the fermionic coordinates and three of the CP^3
directions. We show that the Buscher procedure fails as it leads to a singular
transformation and discuss the result and its implications.Comment: LaTeX2e, 9 pages, no figures, JHEP style; v2: minor clarifications;
v3: typos fixed, matches the published versio
Successful pregnancy following transfer of frozen-thawed embryos in a patient with pseudomyxoma peritonei who underwent peritonectomy and bilateral oophorectomy
Pseudomyxoma peritonei is a rare, chronic relapsing disease in which tumor cells in the abdomen produce excessive mucin with a significant mortality rate. We describe a young unmarried nulligrava who underwent fertility preservation by in vitro fertilisation and embryo cryopreservation prior to radical surgery and adjuvant chemotherapy. Pregnancy was achieved, although complicated by obstructive uropathy. She delivered a healthy infant at 32 weeks' gestation. The few descriptions of fertility and pregnancy outcome in pseudomyxoma peritonei that appear in the literature are reviewed
Integrability of Type II Superstrings on Ramond-Ramond Backgrounds in Various Dimensions
We consider type II superstrings on AdS backgrounds with Ramond-Ramond flux
in various dimensions. We realize the backgrounds as supercosets and analyze
explicitly two classes of models: non-critical superstrings on AdS_{2d} and
critical superstrings on AdS_p\times S^p\times CY. We work both in the
Green--Schwarz and in the pure spinor formalisms. We construct a one-parameter
family of flat currents (a Lax connection) leading to an infinite number of
conserved non-local charges, which imply the classical integrability of both
sigma-models. In the pure spinor formulation, we use the BRST symmetry to prove
the quantum integrability of the sigma-model. We discuss how classical
\kappa-symmetry implies one-loop conformal invariance. We consider the addition
of space-filling D-branes to the pure spinor formalism.Comment: LaTeX2e, 56 pages, 1 figure, JHEP style; v2: references added, typos
fixed in some equations; v3: typos fixed to match the published versio
Semiconductor-based DNA sequencing of histone modification states
The recent development of a semiconductor-based, non-optical DNA sequencing technology promises scalable, low-cost and rapid sequence data production. The technology has previously been applied mainly to genomic sequencing and targeted re-sequencing. Here we demonstrate the utility of Ion Torrent semiconductor-based sequencing for sensitive, efficient and rapid chromatin immunoprecipitation followed by sequencing (ChIP-seq) through the application of sample preparation methods that are optimized for ChIP-seq on the Ion Torrent platform. We leverage this method for epigenetic profiling of tumour tissues
Coherent manipulation of nuclear spins in the strong driving regime
Spin-based quantum information processing makes extensive use of spin-state manipulation. This ranges from dynamical decoupling of nuclear spins in quantum sensing experiments to applying logical gates on qubits in a quantum processor. Fast manipulation of spin states is highly desirable for accelerating experiments, enhancing sensitivity, and applying elaborate pulse sequences. Strong driving using intense radio-frequency (RF) fields can, therefore, facilitate fast manipulation and enable broadband excitation of spin species. In this work, we present an antenna for strong driving in quantum sensing experiments and theoretically address challenges of the strong driving regime. First, we designed and implemented a micron-scale planar spiral RF antenna capable of delivering intense fields to a sample. The planar antenna is tailored for quantum sensing experiments using the diamond's nitrogen-vacancy (NV) center and should be applicable to other solid-state defects. The antenna has a broad bandwidth of 22 MHz, is compatible with scanning probes, and is suitable for cryogenic and ultrahigh vacuum conditions. We measure the magnetic field induced by the antenna and estimate a field-to-current ratio of 113 +/- 16 G/A, representing a six-fold increase in efficiency compared to the state-of-the-art, crucial for cryogenic experiments. We demonstrate the antenna by driving Rabi oscillations in 1H spins of an organic sample on the diamond surface and measure 1H Rabi frequencies of over 500 kHz, i.e. pi -pulses shorter than 1 mu s -an order of magnitude faster than previously reported in NV-based nuclear magnetic resonance (NMR). Finally, we discuss the implications of driving spins with a field tilted from the transverse plane in a regime where the driving amplitude is comparable to the spin-state splitting, such that the rotating wave approximation does not describe the dynamics well. We present a simple recipe to optimize pulse fidelity in this regime based on a phase and offset-shifted sine drive, which may be optimized in situ without numerical optimization procedures or precise modeling of the experiment. We consider this approach in a range of driving amplitudes and show that it is particularly efficient in the case of a tilted driving field. The results presented here constitute a foundation for implementing fast nuclear spin control in various systems
Coherent manipulation of nuclear spins in the strong driving regime
Spin-based quantum information processing makes extensive use of spin-state
manipulation. This ranges from dynamical decoupling of nuclear spins in quantum
sensing experiments to applying logical gates on qubits in a quantum processor.
Here we present an antenna for strong driving in quantum sensing experiments
and theoretically address challenges of the strong driving regime. First, we
designed and implemented a micron-scale planar spiral RF antenna capable of
delivering intense fields to a sample. The planar antenna is tailored for
quantum sensing experiments using the diamond's nitrogen-vacancy (NV) center
and should be applicable to other solid-state defects. The antenna has a broad
bandwidth of 22 MHz, is compatible with scanning probes, and is suitable for
cryogenic and ultrahigh vacuum conditions. We measure the magnetic field
induced by the antenna and estimate a field-to-current ratio of
G/A, representing a x6 increase in efficiency compared to the state-of-the-art.
We demonstrate the antenna by driving Rabi oscillations in H spins of an
organic sample on the diamond surface and measure H Rabi frequencies of
over 500 kHz, i.e., -pulses shorter than 1 - faster than
previously reported in NV-based nuclear magnetic resonance (NMR). Finally, we
discuss the implications of driving spins with a field tilted from the
transverse plane in a regime where the driving amplitude is comparable to the
spin-state splitting, such that the rotating wave approximation does not
describe the dynamics well. We present a recipe to optimize pulse fidelity in
this regime based on a phase and offset-shifted sine drive, that may be
optimized without numerical optimization procedures or precise modeling of the
experiment. We consider this approach in a range of driving amplitudes and show
that it is particularly efficient in the case of a tilted driving field
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