A Comparison of Boosted-Discharge Hollow Cathode Lamps and an Inductively Coupled Plasma (ICP) as Excitation Sources in ICP Atomic Fluorescence Spectrometry

Copper, nickel and lead boosted-discharge hollow cathode lamps, run at recommended currents, have been compared with a high-powered inductively coupled plasma (ICP) as excitation sources in atomic fluorescence spectrometry (AFS). A similar comparison was made with a copper lamp run at higher currents. It was found that for lead and nickel, the fluorescence spectra differed in the relative intensities of the transitions observed with the two sources. No evidence was found for a difference in radiances between the two sources when the lamp was overrun. Although the lamps gave rise to lower blank standard deviation values, detection limits were worse because of poorer sensitivity due to the inability of the circular source to illuminate the required atom cell volume in the atomiser. It was concluded that the ICP was the better source, when the criterion is detection limits, but the lamps may be more convenient in some circumstances

Energy-efficient resource allocation for dual-NOMA-UAV assisted Internet of Things

Employing unmanned aerial vehicles (UAVs) characterized by low cost, high maneuverability, and on-demand deployment as aerial base stations (BSs) of Internet of Things (IoT) can guarantee communication performance in the absence of terrestrial BSs. However, the limited energy budget of UAV constrains its development. In this paper, a dual-UAV-assisted IoT using non-orthogonal multiple access (NOMA) is proposed to improve IoT capacity. To reduce energy consumption of the UAVs while ensuring a certain throughput, a joint resource optimization problem of communication scheduling, transmit power and motion parameters of UAVs is formulated to maximize energy efficiency of UAVs. To solve the proposed non-convex optimization problem, we present an alternating iterative optimization algorithm to alternately optimize three sub-problems: communication scheduling optimization, UAV transmit power optimization and UAV motion parameters optimization, each of which can be converted into convex optimization and solved using Lagrange multiplier method, subgradient descent method and successive convex approximation (SCA). The numerical results show that optimizing UAV motion parameters can effectively improve energy efficiency of UAVs, and the proposed dual-NOMA-UAV assisted IoT can achieve higher energy efficiency than the orthogonal multiple access (OMA)-UAV assisted IoT

Bulk Etch Rate Measurements and Calibrations of Plastic Nuclear Track Detectors

New calibrations of CR39 and Makrofol nuclear track detectors have been obtained using 158 A GeV Pb (82+) and In (49+) ions; a new method for the bulk etch rate determination, using both cone height and base diameter measurements was developed. The CR39 charge resolution based on the etch-pit base area measurement is adequate to identify nuclear fragments in the interval 7 <= Z/beta <= 49. For CR39 the detection threshold is at REL~50 MeV cm^2/g, corresponding to a nuclear fragment with Z/beta~7. Base cone area distributions for Makrofol foils exposed to Pb (82+) ions have shown for the first time all peaks due to nuclear fragments with Z > 50; the distribution of the etched cone heights shows well separated individual peaks for Z/beta = 78 - 83 (charge pickup). The Makrofol detection threshold is at REL 2700 MeV cm^2/g, corresponding to a nuclear fragment with Z/beta~50.Comment: 11 pages, 5 EPS figures. Submitted to Nucl. Instr. Meth.

Electron transport and room temperature single-electron charging in 10 nm scale PtC nanostructures formed by electron beam induced deposition

Nanostructures of platinum-carbon nanocomposite material have been formed by electron-beam induced deposition. These consist of nanodots and nanowires with a minimum size ~20 nm, integrated within ~100 nm nanogap n-type silicon-on-insulator transistor structures. The nanodot transistors use ~20 nm Pt/C nanodots, tunnel-coupled to Pt/C nanowire electrodes, bridging the Si nanogaps. Room-temperature single-electron transistor operation has been measured, and single-electron current oscillations and 'Coulomb diamonds' observed. In nanowire transistors, the temperature dependence from 290 to 8 K suggests that the current is a combination of thermally activated and tunnelling transport of carriers across potential barriers along the current path, and that the Pt/C is p-type at low temperature

Room-temperature measurement of electrostatically coupled, dopant-atom double quantum dots in point-contact transistors

The reduction of nanoelectronic devices to sub-10 nm sizes raises the prospect of electronics at the atomic scale, while also facilitating studies on nanoscale device physics. Single-atom transistors, where the current-switching element is formed by one atom and the information packet size is reduced to one electron, can create electronic switches scaled to their ultimate physical limits. Hitherto, single-atom transistor operation has been limited to low temperatures due to shallow quantum wells, which inhibit room-temperature nanoelectronic applications. Furthermore, the interaction between multiple single-atom elements at room temperature has yet to be demonstrated. Here, we show that quantum interactions between P dopants in Si / Si O 2 / Si single-atom transistors lead to room-temperature double quantum dot behavior. Hexagonal regions of charge stability and gate-controlled tunnel coupling between P atoms are observed at room temperature. Image processing is used to help reduce observer bias in data analysis. Single-electron device simulation is used to investigate evolution of the charge-stability region with varying capacitance and resistance. In combination with extracted tunnel capacitances and resistances, this allows experimental trends to be reproduced and provides information on the dopant-atom arrangement

“How Long Have I Got?”—A Prospective Cohort Study Comparing Validated Prognostic Factors for Use in Patients with Advanced Cancer

© AlphaMed Press 2019 Background: The optimal prognostic factors in patients with advanced cancer are not known, as a comparison of these is lacking. The aim of the present study was to determine the optimal prognostic factors by comparing validated factors. Materials and Methods: A multicenter, prospective observational cohort study recruited patients over 18 years with advanced cancer. The following were assessed: clinician-predicted survival (CPS), Eastern Cooperative Oncology Group performance status (ECOG-PS), patient reported outcome measures (anorexia, cognitive impairment, dyspnea, global health), metastatic disease, weight loss, modified Glasgow Prognostic Score (mGPS) based on C-reactive protein and albumin, lactate dehydrogenase (LDH), and white (WCC), neutrophil (NC), and lymphocyte cell counts. Survival at 1 and 3 months was assessed using area under the receiver operating curve and logistic regression analysis. Results: Data were available on 478 patients, and the median survival was 4.27 (1.86–7.03) months. On univariate analysis, the following factors predicted death at 1 and 3 months: CPS, ECOG-PS, mGPS, WCC, NC (all

Selection of Oncogenic Mutant Clones in Normal Human Skin Varies with Body Site

Skin cancer risk varies substantially across the body, yet how this relates to the mutations found in normal skin is unknown. Here we mapped mutant clones in skin from high- and low-risk sites. The density of mutations varied by location. The prevalence of NOTCH1 and FAT1 mutations in forearm, trunk, and leg skin was similar to that in keratinocyte cancers. Most mutations were caused by ultraviolet light, but mutational signature analysis suggested differences in DNA-repair processes between sites. Eleven mutant genes were under positive selection, with TP53 preferentially selected in the head and FAT1 in the leg. Fine-scale mapping revealed 10% of clones had copy-number alterations. Analysis of hair follicles showed mutations in the upper follicle resembled adjacent skin, but the lower follicle was sparsely mutated. Normal skin is a dense patchwork of mutant clones arising from competitive selection that varies by location. / Significance: Mapping mutant clones across the body reveals normal skin is a dense patchwork of mutant cells. The variation in cancer risk between sites substantially exceeds that in mutant clone density. More generally, mutant genes cannot be assigned as cancer drivers until their prevalence in normal tissue is known