An Efficient Algorithm for Optimizing Adaptive Quantum Metrology Processes

Quantum-enhanced metrology infers an unknown quantity with accuracy beyond the standard quantum limit (SQL). Feedback-based metrological techniques are promising for beating the SQL but devising the feedback procedures is difficult and inefficient. Here we introduce an efficient self-learning swarm-intelligence algorithm for devising feedback-based quantum metrological procedures. Our algorithm can be trained with simulated or real-world trials and accommodates experimental imperfections, losses, and decoherence

Anisotropic Diffusion Limited Aggregation

Using stochastic conformal mappings we study the effects of anisotropic perturbations on diffusion limited aggregation (DLA) in two dimensions. The harmonic measure of the growth probability for DLA can be conformally mapped onto a constant measure on a unit circle. Here we map $m$ preferred directions for growth of angular width $\sigma$ to a distribution on the unit circle which is a periodic function with $m$ peaks in $[-\pi, \pi)$ such that the width $\sigma$ of each peak scales as $\sigma \sim 1/\sqrt{k}$, where $k$ defines the ``strength'' of anisotropy along any of the $m$ chosen directions. The two parameters $(m,k)$ map out a parameter space of perturbations that allows a continuous transition from DLA (for $m=0$ or $k=0$) to $m$ needle-like fingers as $k \to \infty$. We show that at fixed $m$ the effective fractal dimension of the clusters $D(m,k)$ obtained from mass-radius scaling decreases with increasing $k$ from $D_{DLA} \simeq 1.71$ to a value bounded from below by $D_{min} = 3/2$. Scaling arguments suggest a specific form for the dependence of the fractal dimension $D(m,k)$ on $k$ for large $k$, form which compares favorably with numerical results.Comment: 6 pages, 4 figures, submitted to Phys. Rev.

High-order harmonic generation with a strong laser field and an attosecond-pulse train: the Dirac Delta comb and monochromatic limits

In recent publications, it has been shown that high-order harmonic generation can be manipulated by employing a time-delayed attosecond pulse train superposed to a strong, near-infrared laser field. It is an open question, however, which is the most adequate way to approximate the attosecond pulse train in a semi-analytic framework. Employing the Strong-Field Approximation and saddle-point methods, we make a detailed assessment of the spectra obtained by modeling the attosecond pulse train by either a monochromatic wave or a Dirac-Delta comb. These are the two extreme limits of a real train, which is composed by a finite set of harmonics. Specifically, in the monochromatic limit, we find the downhill and uphill sets of orbits reported in the literature, and analyze their influence on the high-harmonic spectra. We show that, in principle, the downhill trajectories lead to stronger harmonics, and pronounced enhancements in the low-plateau region. These features are analyzed in terms of quantum interference effects between pairs of quantum orbits, and compared to those obtained in the Dirac-Delta limit.Comment: 10 pages, 7 figures (eps files). To appear in Laser Physic

FDA and EMA Approvals of New Breast Cancer Drugs—A Comparative Regulatory Analysis

Breast cancer is the most common cancer in women worldwide and the solid tumor type for which the highest number of drugs have been approved to date. This study examines new drug approvals for breast cancer by the United States Food and Drug Administration (FDA) and the European Medicines Agency (EMA), based on an analysis of regulatory documents from both agencies for the period from 1995 to 2018. Of the 29 breast cancer drugs approved over this time span, 17 received positive decisions from both the FDA and EMA, including all drugs licensed after 2008. Nineteen of the 25 FDA-approved drugs, but none of the EMA approvals, benefited from special regulatory pathways (such as fast track, breakthrough therapy, or priority review). In the U.S.A., four accelerated approvals were granted (of which one, for bevacizumab, was later revoked), while only two drugs received provisional approvals following EMA review. New breast cancer drugs were approved approximately twelve months earlier in the United States than in Europe. These results suggest that a broader use of special regulatory pathways by EMA could help to accelerate access to novel drugs for European breast cancer patients

Saccharopolyspora cebuensis sp. nov., a novel actinomycete isolated from a Philippine sponge (Porifera)

The taxonomic status of a marine actinomycete isolated from the sponge Haliclona sp. collected from Cebu, Philippines, was established using both phenotypic and genotypic data. Strain SPE 10-1(T) exhibited chemotaxonomic and morphological characteristics that were consistent with those of members of the genus Saccharopolyspora. It showed a strict requirement for salt and is the first obligate marine bacterium of the genus Saccharopolyspora to be isolated. The principal isoprenoid quinone detected was MK-9(H(4)). The fatty acid pattern consisted mainly of terminally branched iso and anteiso fatty acids. The DNA G+C content was 72.6 mol%. Analysis of the 16S rRNA gene sequence supported affiliation of the strain with the genus Saccharopolyspora; the type strain of Saccharopolyspora gregorii was the closest phylogenetic relative (96 % sequence similarity). Sequence similarities of strain SPE 10-1(T) to other type strains of this genus were 93-95 %. It is proposed that strain SPE 10-1(T) should be classified in the genus Saccharopolyspora as a representative of Saccharopolyspora cebuensis sp. nov. The type strain of Saccharopolyspora cebuensis is SPE 10-1(T) (=DSM 45019(T)=CIP 109355(T))

Ray splitting in paraxial optical cavities

We present a numerical investigation of the ray dynamics in a paraxial optical cavity when a ray splitting mechanism is present. The cavity is a conventional two-mirror stable resonator and the ray splitting is achieved by inserting an optical beam splitter perpendicular to the cavity axis. We show that depending on the position of the beam splitter the optical resonator can become unstable and the ray dynamics displays a positive Lyapunov exponent.Comment: 13 pages, 7 figures, 1 tabl

Rubrobacter aplysinae sp. nov., isolated from the marine sponge Aplysina aerophoba

A Gram-stain-positive, non-spore-forming bacterium (strain RV113(T)) was isolated from the marine sponge Aplysina aerophoba. 16S rRNA gene sequence analysis showed that strain RV113(T) belongs to the genus Rubrobacter, and is related most closely to Rubrobacter bracarensis VF70612_S1(T) (96.9% similarity) and more distantly related (<93%) to all other species of the genus Rubrobacter. The peptidoglycan diamino acid was lysine. Strain RV113(T) exhibited a quinone system with menaquinone MK-8 as the predominant compound. The polar lipid profile of strain RV113(T) consisted of the major compounds phosphatidylglycerol and two unidentified phosphoglycolipids. The major fatty acid was anteiso-C17 : 0ω9c. These chemotaxonomic traits are in agreement with those of other species of the genus Rubrobacter. The results of physiological and biochemical tests allowed the clear phenotypic differentiation of strain RV113(T) from all recognized Rubrobacter species. Strain RV113(T) is thus considered to represent a novel species, for which the name Rubrobacter aplysinae sp. nov. is proposed. The type strain is RV113(T) ( = DSM 27440(T) = CECT 8425(T))

Absorption of Ultrashort Laser Pulses in Strongly Overdense Targets

We report on the first absorption experiments of sub-10 fs high-contrast Ti:Sa laser pulses incident on solid targets. The very good contrast of the laser pulse assures the formation of a very small pre-plasma and the pulse interacts with the matter close to solid density. Experimental results indicate that p-polarized laser pulses are absorbed up to 80 percent at 80 degrees incidence angle. The simulation results of PSC PIC code clearly confirm the observations and show that the collisionless absorption works efficiently in steep density profiles