239 research outputs found
Two-loop AdS_5 x S^5 superstring: testing asymptotic Bethe ansatz and finite size corrections
We continue the investigation of two-loop string corrections to the energy of
a folded string with a spin S in AdS_5 and an angular momentum J in S^5, in the
scaling limit of large J and S with ell=pi J/(lambda^(1/2) ln S)=fixed. We
compute the generalized scaling function at two-loop order f_2(ell) both for
small and large values of ell matching the predictions based on the asymptotic
Bethe ansatz. In particular, in the small ell expansion, we derive an exact
integral form for the ell-dependent coefficient of the Catalan's constant term
in f_2(ell). Also, by resumming a certain subclass of multi-loop Feynman
diagrams we obtain an exact expression for the leading (ln ell) part of
f(lambda^(1/2), ell) which is valid to any order in the alpha'~1/lambda^(1/2)
expansion. At large ell the string energy has a BMN-like expansion and the
first few leading coefficients are expected to be the same at weak and at
strong coupling. We provide a new example of this non-renormalization for the
term which is generated at two loops in string theory and at one-loop in gauge
theory (sub-sub-leading in 1/J). We also derive a simple algebraic formula for
the term of maximal transcendentality in f_2(ell) expanded at large ell. In the
second part of the paper we initiate the study of 2-loop finite size
corrections to the string energy by formally compactifying the spatial
world-sheet direction in the string action expanded near long fast-spinning
string. We observe that the leading finite-size corrections are of "Casimir"
type coming from terms containing at least one massless propagator. We consider
in detail the one-loop order (reproducing the leading Landau-Lifshitz model
prediction) and then focus on the two-loop contributions to the (1/ln S) term
(for J=0). We find that in a certain regularization scheme used to discard
power divergences the two-loop coefficient of the (1/ln S) term appears to
vanish.Comment: 50 pages, 4 figures v2: typos corrected, references adde
Controlling trapping potentials and stray electric fields in a microfabricated ion trap through design and compensation
Recent advances in quantum information processing with trapped ions have
demonstrated the need for new ion trap architectures capable of holding and
manipulating chains of many (>10) ions. Here we present the design and detailed
characterization of a new linear trap, microfabricated with scalable
complementary metal-oxide-semiconductor (CMOS) techniques, that is well-suited
to this challenge. Forty-four individually controlled DC electrodes provide the
many degrees of freedom required to construct anharmonic potential wells,
shuttle ions, merge and split ion chains, precisely tune secular mode
frequencies, and adjust the orientation of trap axes. Microfabricated
capacitors on DC electrodes suppress radio-frequency pickup and excess
micromotion, while a top-level ground layer simplifies modeling of electric
fields and protects trap structures underneath. A localized aperture in the
substrate provides access to the trapping region from an oven below, permitting
deterministic loading of particular isotopic/elemental sequences via
species-selective photoionization. The shapes of the aperture and
radio-frequency electrodes are optimized to minimize perturbation of the
trapping pseudopotential. Laboratory experiments verify simulated potentials
and characterize trapping lifetimes, stray electric fields, and ion heating
rates, while measurement and cancellation of spatially-varying stray electric
fields permits the formation of nearly-equally spaced ion chains.Comment: 17 pages (including references), 7 figure
Demonstration of integrated microscale optics in surface-electrode ion traps
In ion trap quantum information processing, efficient fluorescence collection
is critical for fast, high-fidelity qubit detection and ion-photon
entanglement. The expected size of future many-ion processors require scalable
light collection systems. We report on the development and testing of a
microfabricated surface-electrode ion trap with an integrated high numerical
aperture (NA) micromirror for fluorescence collection. When coupled to a low NA
lens, the optical system is inherently scalable to large arrays of mirrors in a
single device. We demonstrate stable trapping and transport of 40Ca+ ions over
a 0.63 NA micromirror and observe a factor of 1.9 enhancement in photon
collection compared to the planar region of the trap.Comment: 15 pages, 8 figure
From Scattering Amplitudes to the Dilatation Generator in N=4 SYM
The complete spin chain representation of the planar N=4 SYM dilatation
generator has long been known at one loop, where it involves leading
nearest-neighbor 2 -> 2 interactions. In this work we use superconformal
symmetry to derive the unique solution for the leading L -> 2 interactions of
the planar dilatation generator for arbitrarily large L. We then propose that
these interactions are given by the scattering operator that has N=4 SYM
tree-level scattering amplitudes as matrix elements. We provide compelling
evidence for this proposal, including explicit checks for L=2,3 and a proof of
consistency with superconformal symmetry.Comment: 39 pages, v2: reference added and minor changes, published versio
Nonperturbative scales in AdS/CFT
The cusp anomalous dimension is a ubiquitous quantity in four-dimensional
gauge theories, ranging from QCD to maximally supersymmetric N=4 Yang-Mills
theory, and it is one of the best investigated observables in the AdS/CFT
correspondence. In planar N=4 SYM theory, its perturbative expansion at weak
coupling has a finite radius of convergence while at strong coupling it admits
an expansion in inverse powers of the 't Hooft coupling which is given by a
non-Borel summable asymptotic series. We study the cusp anomalous dimension in
the transition regime from strong to weak coupling and argue that the
transition is driven by nonperturbative, exponentially suppressed corrections.
To compute these corrections, we revisit the calculation of the cusp anomalous
dimension in planar N=4 SYM theory and extend the previous analysis by taking
into account nonperturbative effects. We demonstrate that the scale
parameterizing nonperturbative corrections coincides with the mass gap of the
two-dimensional bosonic O(6) sigma model embedded into the AdS_5xS^5 string
theory. This result is in agreement with the prediction coming from the string
theory consideration.Comment: 49 pages, 1 figure; v2: minor corrections, references adde
TBA-like equations and Casimir effect in (non-)perturbative AdS/CFT
We consider high spin, , long twist, , planar operators (asymptotic
Bethe Ansatz) of strong SYM. Precisely, we compute the minimal
anomalous dimensions for large 't Hooft coupling to the lowest order
of the (string) scaling variable with GKP string size . At the leading order ,
we can confirm the O(6) non-linear sigma model description for this bulk term,
without boundary term . Going further, we derive,
extending the O(6) regime, the exact effect of the size finiteness. In
particular, we compute, at all loops, the first Casimir correction (in terms of the infinite size O(6) NLSM), which reveals only one
massless mode (out of five), as predictable once the O(6) description has been
extended. Consequently, upon comparing with string theory expansion, at one
loop our findings agree for large twist, while reveal for negligible twist,
already at this order, the appearance of wrapping. At two loops, as well as for
next loops and orders, we can produce predictions, which may guide future
string computations.Comment: Version 2 with: new exact expression for the Casimir energy derived
(beyond the first two loops of the previous version); UV theory formulated
and analysed extensively in the Appendix C; origin of the O(6) NLSM
scattering clarified; typos correct and references adde
Allogeneic hematopoietic cell transplantation for multiple myeloma in Europe: trends and outcomes over 25 years. A study by the EBMT Chronic Malignancies Working Party
We describe the use and outcomes of allogeneic hematopoietic stem cell transplantation (allo-HSCT) for multiple myeloma (MM) in Europe between January 1990 and December 2012. We identified 7333 patients, median age at allo-HSCT was 51 years (range: 18-78), of whom 4539 (62%) were males. We distinguished three groups: (1) allo-HSCT upfront (n=1924), (2) tandem auto-allo-HSCT (n=2004) and (3) allo-HSCT as a second line treatment and beyond (n=3405). Overall, there is a steady increase in numbers of allo-HSCT over the years. Upfront allo-HSCT use increased up to year 2000, followed by a decrease thereafter and represented 12% of allo-HSCTs performed in 2012. Tandem auto-allo-HSCT peaked around year 2004 and contributed to 19% of allo-HSCTs in 2012. Allo-HSCT as salvage after one or two or three autografts was steadily increasing over the last years and represented 69% of allo-HSCTs in 2012. Remarkable heterogeneity in using allo-HSCT was observed among the different European countries. The 5-year survival probabilities from time of allo-HSCT for the three groups after year 2004 were 42%, 54% and 32%, respectively. These results show that the use of allo-HSCT is increasing in Europe, especially as second line treatment and beyond. There is an unmet need for well-designed prospective studies investigating allo-HSCT as salvage therapy for MM
Quantum folded string and integrability: from finite size effects to Konishi dimension
Using the algebraic curve approach we one-loop quantize the folded string
solution for the type IIB superstring in AdS(5)xS(5). We obtain an explicit
result valid for arbitrary values of its Lorentz spin S and R-charge J in terms
of integrals of elliptic functions. Then we consider the limit S ~ J ~ 1 and
derive the leading three coefficients of strong coupling expansion of short
operators. Notably, our result evaluated for the anomalous dimension of the
Konishi state gives 2\lambda^{1/4}-4+2/\lambda^{1/4}. This reproduces correctly
the values predicted numerically in arXiv:0906.4240. Furthermore we compare our
result using some new numerical data from the Y-system for another similar
state. We also revisited some of the large S computations using our methods. In
particular, we derive finite--size corrections to the anomalous dimension of
operators with small J in this limit.Comment: 20 pages, 1 figure; v2: references added, typos corrected; v3: major
improvement of the references; v4: Discussion of short operators is
restricted to the case n=1. This restriction does not affect the main results
of the pape
Liver Transplantation because of Acute Liver Failure due to Heme Arginate Overdose in a Patient with Acute Intermittent Porphyria
In acute attacks of acute intermittent porphyria, the mainstay of treatment is glucose and heme arginate administration. We present the case of a 58-year-old patient with acute liver failure requiring urgent liver transplantation after erroneous 6-fold overdose of heme arginate during an acute attack. As recommended in the product information, albumin and charcoal were administered and hemodiafiltration was started, which could not prevent acute liver failure, requiring super-urgent liver transplantation after 6 days. The explanted liver showed no preexisting liver cirrhosis, but signs of subacute liver injury and starting regeneration. The patient recovered within a short time. A literature review revealed four poorly documented cases of potential hepatic and/or renal toxicity of hematin or heme arginate. This is the first published case report of acute liver failure requiring super-urgent liver transplantation after accidental heme arginate overdose. The literature and recommendations in case of heme arginate overdose are summarized. Knowledge of a potentially fatal course is important for the management of future cases. If acute liver failure in case of heme arginate overdose is progressive, super-urgent liver transplantation has to be evaluated
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