Signal Processing on Waveform Data from the Eyesafe Ladar Testbed (ELT)

The Eyesafe Ladar Test-bed (ELT) is a raster scanning, single-beam, energy-detection ladar with the capability of digitizing and recording the return pulse waveform at 2 GHz in the field for off-line 3D point cloud formation research in the laboratory. The ELT serves as a prime tool in understanding the behavior of ladar waveforms. Signal processing techniques have been applied to the ELT waveform in an effort to exploit the signal with respect to noise reduction, range resolution improvement, and ability to discriminate between two surfaces of similar range. This paper presents a signal processing method used on the ELT waveform. In the processing, three deconvolution techniques were investigated-the Wiener filter, Richardson-Lucy deconvolution, and a new method that synthesizes the surface response using least squares minimization. Range error and range resolution are reported for these methods

Simulation and Modeling of Return Waveforms from a Ladar Beam Footprint in USU LadarSIM

Ladar systems are an emerging technology with applications in many fields. Consequently, simulations for these systems have become a valuable tool in the improvement of existing systems and the development of new ones. This paper discusses the theory and issues involved in reliably modeling the return waveform of a ladar beam footprint in the Utah State University LadarSIM simulation software. Emphasis is placed on modeling system-level effects that allow an investigation of engineering tradeoffs in preliminary designs, and validation of behaviors in fabricated designs. Efforts have been made to decrease the necessary computation time while still maintaining a usable model. A full waveform simulation is implemented that models optical signals received on detector followed by electronic signals and discriminators commonly encountered in contemporary direct-detection ladar systems. Waveforms are modeled using a novel hexagonal sampling process applied across the ladar beam footprint. Each sample is weighted using a Gaussian spatial profile for a well formed laser footprint. Model fidelity is also improved by using a bidirectional reflectance distribution function (BRDF) for target reflectance. Once photons are converted to electrons, waveform processing is used to detect first, last or multiple return pulses. The detection methods discussed in this paper are a threshold detection method, a constant fraction method, and a derivative zero-crossing method. Various detection phenomena, such as range error, walk error, drop outs and false alarms, can be studied using these detection methods

A Handheld Texel Camera for Acquiring Near-Instantaneous 3D Images

A Texel camera is a device which synchronously captures depth information via a ladar and digital imagery of the same scene. The ladar and digital camera are co-boresighted to eliminate parallax. This configuration fuses the ladar data to the digital image at the pixel level, eliminating complex post-processing to register the datasets. This paper describes a handheld version of a Texel Camera which can be used to create near-instantaneous 3D imagery. The hardware configuration of the Texel Camera, issues and method associated with ladar/camera calibration, and representative imagery are presented

Solid‐Phase Supports for Oligonucleotide Synthesis

This unit begins with a discussion of the advantages and disadvantages of oligonucleotide synthesis using solid supports. The physical and chemical properties of solid‐phase supports are discussed in terms of their suitability for oligonucleotide synthesis. In addition, the unit outlines the properties of linkers used for transient or permanent attachment of properly protected nucleosides to the derivatized support, as well as strategies for coupling nucleosides to linkers and conditions for the release of synthetic oligonucleotides from specific supports.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143613/1/cpnc0301.pd

Distributed Approximation of Minimum Routing Cost Trees

We study the NP-hard problem of approximating a Minimum Routing Cost Spanning Tree in the message passing model with limited bandwidth (CONGEST model). In this problem one tries to find a spanning tree of a graph $G$ over $n$ nodes that minimizes the sum of distances between all pairs of nodes. In the considered model every node can transmit a different (but short) message to each of its neighbors in each synchronous round. We provide a randomized $(2+\epsilon)$-approximation with runtime $O(D+\frac{\log n}{\epsilon})$ for unweighted graphs. Here, $D$ is the diameter of $G$. This improves over both, the (expected) approximation factor $O(\log n)$ and the runtime $O(D\log^2 n)$ of the best previously known algorithm. Due to stating our results in a very general way, we also derive an (optimal) runtime of $O(D)$ when considering $O(\log n)$-approximations as done by the best previously known algorithm. In addition we derive a deterministic $2$-approximation

LHCD during current ramp experiments on Alcator C-Mod

The lower hybrid current drive (LHCD) system on Alcator C-Mod is capable of sustaining fully non-inductive discharges for multiple current relaxation times (τcr ∼ 200 ms) at line averaged densities in the range of 5x1019 m-3. Some of these non-inductive discharges develop unstable MHD modes that can greatly reduce current drive performance, particularly in discharges with plasma current of 0.5 MA or less [1,2]. Avoiding these unstable MHD modes motivated an experiment to test if the stable current profile shape of a higher current non-inductive discharge could be achieved in a lower current discharge. Starting from a discharge at 0.8 MA, the plasma current was ramped down to 0.5 MA over 200 ms. The surface voltage of the plasma swings negative during the ramp, with the loop voltage reversal impacting the edge fast electron measurements immediately. Little change can be seen during the Ip ramp in the core fast electron measurements, indicating that the loop voltage reversal does not penetrate fully to the magnetic axis on the timescale of the current ramp. The resulting discharge did not exhibit deleterious MHD instabilities, however the existence of this one discharge does not necessarily represent a robust solution to the problem

Radiofrequency Ablation Resulting in Left Lobe Hypertrophy and Improved Resectability

Surgical resection for colorectal liver metastases may only be considered when an adequate functional residual volume can be preserved. Selective portal venous embolisation may be used to increase this volume, whilst chemotherapy and radiofrequency ablation (RFA) can be used to treat inoperable lesions. A 73-year-old man with liver metastasis proceeded to surgery, with the intention to perform a right hemi-hepatectomy. Unexpectedly at laparotomy, despite adequate pre-operative imaging, both the right and middle hepatic veins were involved. At that time extended right hemi-hepatectomy was contraindicated by insufficient residual volume and RFA was performed. Follow-up imaging revealed atrophy of the lesion. Significantly, there was also left lateral lobe hypertrophy sufficient to permit resection, which was performed without complication. Thrombosis of intra-hepatic portal veins is a recognised complication of RFA but here it appears to have been beneficial. The case highlights the need for regular review of unresectable hepatic disease by a liver surgeon and could suggest new modalities of portal embolisation

Preparation and Solid-state Structural, Electronic, and Magnetic Properties of the 5-Cyano-1,3-benzene-Bridged Bis(1,2,3,5-dithiadiazolyl) and Bis(1,2,3,5-diselenadiazolyl) [5-CN-1,3-C6H3(CN2E2)2] (E = S, Se)

The preparation and solid-state characterization of the bifunctional radicals [4,4’-(5-cyanobenzene)-1,3-bis(1,2,3,5-dithiadiazolyl)] and [4,4’-(5-cyanobenzene)-1,3-bis( 1,2,3,5-diselenadiazolyl)] [5-CN-1,3-C6H3(CN2E2)2] (E = S, Se) are described. The crystals of the two title compounds are isomorphous and belong to the monoclinic space group P21/c, with (for E = S) a = 7.00(2), b = 30.050(6), c = 10.713(8) Å, β = 104.80(10)°, V = 2179(6) Å3, Z = 8 and (for E = Se) a = 7.124(4), b = 30.50(2), c = 10.874(2) Å, β = 105.46(3)°, V = 2277(2) Å3, Z = 8. The crystal structures consist of stacks of diradicals running parallel to x; radical dimerization up and down the stack generates a zigzag arrangement, as seen in the related 1,3-phenylene structures. Along the stacking axis the mean intradimer E-E contacts are 3.12 (E = S) and 3.23 Å (E = Se), while the mean interdimer E- - -E distances are 3.89 (E = S) and 3.91 Å (E = Se). Magnetic and conductivity data are presented and discussed in light of extended Hückel band structure calculations

Constraining the period of the ringed secondary companion to the young star J1407 with photographic plates

Context. The 16 Myr old star 1SWASP J140747.93-394542.6 (V1400 Cen) underwent a series of complex eclipses in May 2007, interpreted as the transit of a giant Hill sphere filling debris ring system around a secondary companion, J1407b. No other eclipses have since been detected, although other measurements have constrained but not uniquely determined the orbital period of J1407b. Finding another eclipse towards J1407 will help determine the orbital period of the system, the geometry of the proposed ring system and enable planning of further observations to characterize the material within these putative rings. Aims. We carry out a search for other eclipses in photometric data of J1407 with the aim of constraining the orbital period of J1407b. Methods. We present photometry from archival photographic plates from the Harvard DASCH survey, and Bamberg and Sonneberg Observatories, in order to place additional constraints on the orbital period of J1407b by searching for other dimming and eclipse events. Using a visual inspection of all 387 plates and a period-folding algorithm we performed a search for other eclipses in these data sets. Results. We find no other deep eclipses in the data spanning from 1890 to 1990, nor in recent time-series photometry from 2012-2018. Conclusions. We rule out a large fraction of putative orbital periods for J1407b from 5 to 20 years. These limits are still marginally consistent with a large Hill sphere filling ring system surrounding a brown dwarf companion in a bound elliptical orbit about J1407. Issues with the stability of any rings combined with the lack of detection of another eclipse, suggests that J1407b may not be bound to J1407.Comment: 8 pages, 3 tables, 4 figures, accepted for publication in A&A. LaTeX files of the paper, scripts for the figures, and a minimal working FPA can be found under https://github.com/robinmentel/Constraining-Period

KrasMAS: Implementation of a nuclear material computerized accounting system at the Mining and Chemical Combine through the Russian/US cooperative MPC and A program

The Russian/US Mining and Chemical Combine (Gorno-Kimichesky Kombinat, GKhK, also referred to as Krasnoyarsk-26) Material Protection, Control and Accounting (MPC and A) project was initiated in June 1996. A critical component of the ongoing cooperative MPC and A enhancements at the GKhK is the implementation of a computerized nuclear material control and accountability (MC and A) system. This system must meet the MC and A requirements of the GKhK by integrating the information generated by numerous existing and new MC and A components in place at the GKhK (e.g., scales, bar-code equipment, NDA measurement systems). During the first phase of this effort, the GKhK adapted CoreMAS (developed at Los Alamos National Laboratory) for use in the PuO{sub 2} storage facility. This included formulation of Web-based user interfaces for plant personnel, Russification of the existing user interface, and at the functional level, modification of the CoreMAS stored procedures. The modified system is referred to as KrasMAS and builds upon completed work on CoreMAS. Ongoing efforts include adding GKhK specific report forms and expanding the functionality of the system for implementation at the radiochemical processing and reactor plants of the GKhK. Collaborations with other Russian facilities for appropriate parts of these efforts will be pursued