The controlled-drift detector,”

Abstract A new position-sensing X-ray detector is presented. The novel device is called Controlled-Drift Detector (CDD). The detector is fully depleted and is operated by switching between integration and drift modes. The relevant details of the detector design are discussed. A complete experimental characterization of the fast readout of the integrated signal charges achievable with static drift "elds in the range 100}400 V/cm has been carried out. Preliminary measurements to evaluate the charge-handling capacity are also shown. The CDD can provide unambiguous two-dimensional position measurement, high-resolution X-ray spectroscopy and time resolution below 1 ms

Spectroscopic-Grade X-Ray Imaging up to 100-kHz Frame Rate With Controlled-Drift Detectors

Abstract-Controlled-drift detectors are fully depleted silicon detectors for X-ray imaging that combine good position resolution with very fast frame readout. The basic feature of the controlled-drift detector is the transport of the charge packets stored in each pixel column to the output electrode by means of a uniform drift field. The drift time of the charge packet identifies the pixel of incidence. Images of an X-ray source obtained with the controlled-drift detector up to 100-kHz frame rate are presented and discussed. The achievable energy resolution as a function of the operating temperature and frame rate is analyzed. Index Terms-Controlled-drift detector, fast readout, X-ray imaging

Spectroscopic-grade X-ray imaging up to 100 kHz frame rate with controlled-drift detectors

Controlled-drift detectors are fully depleted silicon detectors for X-ray imaging that combine good position resolution with very fast frame readout. The basic feature of the controlled-drift detector is the transport of the charge packets stored in each pixel column to the output electrode by means of a uniform drift field. The drift time of the charge packet identifies the pixel of incidence. Images of an X-ray source obtained with the controlled-drift detector up to 100-kHz frame rate are presented and discussed. The achievable energy resolution as a function of the operating temperature and frame rate is analyzed

Feynman-Kac representation of fully nonlinear PDEs and applications

The classical Feynman-Kac formula states the connection between linear parabolic partial differential equations (PDEs), like the heat equation, and expectation of stochastic processes driven by Brownian motion. It gives then a method for solving linear PDEs by Monte Carlo simulations of random processes. The extension to (fully)nonlinear PDEs led in the recent years to important developments in stochastic analysis and the emergence of the theory of backward stochastic differential equations (BSDEs), which can be viewed as nonlinear Feynman-Kac formulas. We review in this paper the main ideas and results in this area, and present implications of these probabilistic representations for the numerical resolution of nonlinear PDEs, together with some applications to stochastic control problems and model uncertainty in finance

Robust maximization of asymptotic growth under covariance uncertainty

This paper resolves a question proposed in Kardaras and Robertson [Ann. Appl. Probab. 22 (2012) 1576-1610]: how to invest in a robust growth-optimal way in a market where precise knowledge of the covariance structure of the underlying assets is unavailable. Among an appropriate class of admissible covariance structures, we characterize the optimal trading strategy in terms of a generalized version of the principal eigenvalue of a fully nonlinear elliptic operator and its associated eigenfunction, by slightly restricting the collection of nondominated probability measures.Comment: Published in at http://dx.doi.org/10.1214/12-AAP887 the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org

Auroral particles

The problems concerning the aurora posed prior to the war are now either solved in principle or were restated in a more fundamental form. The pre-war hypothesis concerning the nature of the auroral particles and their energies was fully confirmed, with the exception that helium and oxygen ions were identified as participating in the auroral particle precipitation in addition to the protons. The nature of the near-Earth energization processes affecting auroral particles was clarified. Charged particle trajectories in various electric field geometries were modeled. The physical problems have now moved from determining the nature and geometry of the electric fields, which accelerate charged particles near the Earth, to accounting for the existence of these electric fields as a natural consequence of the solar wind's interaction with Earth. Ultimately the reward in continuing the work in auroral and magnetospheric particle dynamics will be a deeper understanding of the subtleties of classical electricity and magnetism as applied to situations not blessed with well-defined and invariant geometries

NASA to launch second business communications satellite

The two stage Delta 3910 launch vehicle was chosen to place the second small business satellite (SBS-B) into a transfer orbit with an apogee of 36,619 kilometers and a perigee of 167 km, at an inclination of 27.7 degrees to Earth's equator. The firing and separation sequence and the inertial guidance system are described as well as the payload assist module. Facilities and services for tracking and control by NASA, COMSAT, Intelsat, and SBS are outlined and prelaunch operations are summarized

Molecular Lysine Tweezers Counteract Aberrant Protein Aggregation.

Molecular tweezers (MTs) are supramolecular host molecules equipped with two aromatic pincers linked together by a spacer (Gakh, 2018). They are endowed with fascinating properties originating from their ability to hold guests between their aromatic pincers (Chen and Whitlock, 1978; Zimmerman, 1991; Harmata, 2004). MTs are finding an increasing number of medicinal applications, e.g., as bis-intercalators for DNA such as the anticancer drug Ditercalinium (Gao et al., 1991), drug activity reverters such as the bisglycoluril tweezers Calabadion 1 (Ma et al., 2012) as well as radioimmuno detectors such as Venus flytrap clusters (Paxton et al., 1991). We recently embarked on a program to create water-soluble tweezers which selectively bind the side chains of lysine and arginine inside their cavity. This unique recognition mode is enabled by a torus-shaped, polycyclic framework, which is equipped with two hydrophilic phosphate groups. Cationic amino acid residues are bound by the synergistic effect of disperse, hydrophobic, and electrostatic interactions in a kinetically fast reversible process. Interactions of the same kind play a key role in numerous protein-protein interactions, as well as in pathologic protein aggregation. Therefore, these particular MTs show a high potential to disrupt such events, and indeed inhibit misfolding and self-assembly of amyloidogenic polypeptides without toxic side effects. The mini-review provides insight into the unique binding mode of MTs both toward peptides and aggregating proteins. It presents the synthesis of the lead compound CLR01 and its control, CLR03. Different biophysical experiments are explained which elucidate and help to better understand their mechanism of action. Specifically, we show how toxic aggregates of oligomeric and fibrillar protein species are dissolved and redirected to form amorphous, benign assemblies. Importantly, these new chemical tools are shown to be essentially non-toxic in vivo. Due to their reversible moderately tight binding, these agents are not protein-, but rather process-specific, which suggests a broad range of applications in protein misfolding events. Thus, MTs are highly promising candidates for disease-modifying therapy in early stages of neurodegenerative diseases. This is an outstanding example in the evolution of supramolecular concepts toward biological application