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During glacial times, the North Atlantic region was affected by serious climate changes corresponding to Dansgaard-Oeschger cycles that were linked to dramatic shifts in sea temperature and moisture transfer to the continents. However, considerable efforts are still needed to understand the effects of these shifts on terrestrial environments. In this context, the Iberian Peninsula is particularly interesting because of its close proximity to the North Atlantic, although the Iberian interior lacks paleoenvironmental information so far because suitable archives are rare. Here we provide an accurate impression of the last glacial environmental developments in central Iberia based on comprehensive investigations using the upper Tagus loess record. A multi-proxy approach revealed that phases of loess formation during Marine Isotope Stage (MIS) 2 (and upper MIS 3) were linked to utmost aridity, coldness, and highest wind strengths in line with the most intense Greenland stadials also including Heinrich Events 3–1. Lack of loess deposition during the global last glacial maximum (LGM) suggests milder conditions, which agrees with less-cold sea surface temperatures (SST) off the Iberian margin. Our results demonstrate that geomorphological system behavior in central Iberia is highly sensitive to North Atlantic SST fluctuations, thus enabling us to reconstruct a detailed hydrological model in relation to marine–atmospheric circulation patterns.
This paper presents a novel GaN-based digital outphasing power amplifier (PA) for the 800 MHz range. The PA reaches a maximum output power of 5.8 W at 30 V final-stage (FS) drain supply voltage. A novel output combiner circuit is used and efficiency is improved by resonant commutation of the FSs and optimized driver circuits for the two GaN push-pull FSs. 3D electromagnetic simulation of output network has been conducted to extract an equivalent circuit model and to access full information in terms of functionality and broadband impedance characteristics for optimized outphasing operation in the final design. Measured total efficiencies (ηtot) of 59 and 25% at 0 and 10 dB power back-off are achieved, respectively, fitting the simulation quite well. The proposed digital outphasing module is a promising candidate for fully digitized base-station architectures in future wireless communications.
Alteplase is an effective treatment for ischaemic stroke patients, and it is widely available at all primary stroke centres. The effectiveness of alteplase is highly time-dependent. Large tertiary centres have reported significant improvements in their door-to-needle (DTN) times. However, these same improvements have not been reported at community hospitals.
Red Deer Regional Hospital Centre (RDRHC) is a community hospital of 370 beds that serves approximately 150,000 people in their acute stroke catchment area. The RDRHC participated in a provincial DTN improvement initiative, and implemented a streamlined algorithm for the treatment of stroke patients. During this intervention period, they implemented the following changes: early alert of an incoming acute stroke patient to the neurologist and care team, meeting the patient immediately upon arrival, parallel work processes, keeping the patient on the Emergency Medical Service stretcher to the CT scanner, and administering alteplase in the imaging area. Door-to-needle data were collected from July 2007 to December 2017.
A total of 289 patients were treated from July 2007 to December 2017. In the pre-intervention period, 165 patients received alteplase and the median DTN time was 77 minutes [interquartile range (IQR): 60–103 minutes]; in the post-intervention period, 104 patients received alteplase and the median DTN time was 30 minutes (IQR: 22–42 minutes) (p < 0.001). The annual number of patients that received alteplase increased from 9 to 29 in the pre-intervention period to annual numbers of 41 to 63 patients in the post-intervention period.
Community hospitals staffed with community neurologists can achieve median DTN times of 30 minutes or less.
The present study is dealing with the basic physics for a novel way to generate a free-formed ceramic body, not like common layer by layer, but directly by Selective Volume Sintering (SVS) in a compact block of ceramic powder. To penetrate with laser light into the volume of a ceramic powder compact it is necessary to investigate the light scattering properties of ceramic powders. Compared with polymers and metals, ceramic materials are unique as they offer a wide optical window of transparency. The optical window typically ranges from below 0.3 up to 5 µm wave length. In the present study thin layers of quartz glass (SiO2) particles have been prepared. As a function of layer thickness and the particle size, transmission and reflection spectra in a wave length range between 0.5 and 2.5 µm have been recorded. Depending on the respective particle size and by choosing a proper relation between particle size and wave length of the incident laser radiation, it is found that light can penetrate a powder compact up to a depth of a few millimeters. With an adjustment of the light absorption properties of the compact the initiation of sintering in the volume of the compact is possible.
Wartime naval builders in the United States constructed the world's largest fleet that defeated the Japanese Imperial Navy, aided the Allied victory during the Battle of the Atlantic, and projected American naval power into all corners of the globe. Many naval combatants were built by highly experienced shipbuilders who possessed advanced design skills and production capabilities that had been years in the making. The present study examines the structures and dynamics of American naval shipbuilding and compares them to their foreign counterparts; it argues that extant capabilities were vital to the success of the U.S. war economy.
The paper presents millimeter-wave (mm-wave) signal sources using a hetero-integrated InP-on-BiCMOS semiconductor technology. Mm-wave signal sources feature fundamental frequency voltage-controlled oscillators (VCOs) in BiCMOS, which drive frequency multiplier–amplifier chains in transferred-substrate (TS) InP-DHBT technology, heterogeneously integrated on top of the BiCMOS wafer in a wafer-level bonding process. Both circuits are biased through a single set of bias pads and compact low-loss transitions from BiCMOS to InP circuits and vice versa have been developed, which allows seamless signal routing through both technologies exhibiting 0.5 dB insertion loss up to 200 GHz. One VCO operates at 82 GHz with a tuning range of 600 MHz and an output power of approximately 8 dBm. A frequency doubler combined with this VCO circuit delivers 0 dBm at 164 GHz and a frequency tripler with a similar VCO delivers −10 dBm at 246 GHz. Another hetero-integrated W-band doubler–amplifier circuit demonstrates 12.9 dBm saturated output power with 5.9 dB conversion gain at 96 GHz. A direct comparison of the TS InP-DHBT MMIC with either silicon or traditional AlN carrier substrates shows the favorable properties of the hetero-integrated process discussed here. The results demonstrate the feasibility of hetero-integrated circuits operating well above 100 GHz.
In this paper, the small- and large-signal modeling of InP heterojunction bipolar transistors (HBTs) in transferred substrate (TS) technology is investigated. The small-signal equivalent circuit parameters for TS-HBTs in two-terminal and three-terminal configurations are determined by employing a direct parameter extraction methodology dedicated to III–V based HBTs. It is shown that the modeling of measured S-parameters can be improved in the millimeter-wave frequency range by augmenting the small-signal model with a description of AC current crowding. The extracted elements of the small-signal model structure are employed as a starting point for the extraction of a large-signal model. The developed large-signal model for the TS-HBTs accurately predicts the DC over temperature and small-signal performance over bias as well as the large-signal performance at millimeter-wave frequencies.
Reconfigurable nanowire transistors provide the operation of unipolar p-type and n-type FETs freely selectable within a single device. The enhanced functionality is enabled by controlling the currents through two individually gated Schottky junctions. Here we analyze the impact of the Schottky barrier height on the symmetry of Silicon nanowire RFET transfer characteristics and their performance within circuits. Prospective simulations are carried out, indicating that germanium nanowire based RFETs of the same dimensions will show a distinctly increased performance, making them a promising material solution for future reconfigurable electronics.
An overview about the German cluster project Cool Silicon aiming at increasing the energy efficiency for semiconductors, communications, sensors and software is presented. Examples for achievements are: 1000 times reduced gate leakage in transistors using high-fc (HKMG) materials compared to conventional poly-gate (SiON) devices at the same technology node; 700 V transistors integrated in standard 0.35 μm CMOS; solar cell efficiencies above 19% at < 200 W/m2 irradiation; 0.99 power factor, 87% efficiency and 0.088 distortion factor for dc supplies; 1 ns synchronization resolution via Ethernet; database accelerators allowing 85% energy savings for servers; adaptive software yielding energy reduction of 73% for e-Commerce applications; processors and corresponding data links with 40% and 70% energy savings, respectively, by adaption of clock frequency and supply voltage in less than 20 ns; clock generator chip with tunable frequency from 83-666 MHz and 0.62-1.6 mW dc power; 90 Gb/s on-chip link over 6 mm and efficiency of 174 fJ/mm; dynamic biasing system doubling efficiency in power amplifiers; 60 GHz BiCMOS frontends with dc power to bandwidth ratio of 0.17 mW/MHz; driver assistance systems reducing energy consumption by 10% in cars
In this contribution, we report on the optimization of a metal-organic decomposition (MOD) ink based on silver(I) complexes by a systematic variation of the ink formulation. As a result, three different ink concepts turned out to be printable and resulting in a sufficiently high contour definition, layer homogeneity, and conductivity. The ink concepts include increase of the solid load, the usage of N-methyl-2-pyrrolidone (NMP) as a humectant with low vapor pressure, addition of co-solvents such as diethylene glycole and addition of sodium lauryl sulfate (SLS) as stabilizing ligand. It turns out that, for silver precursor concentrations of 40 wt%, the addition of 1 wt% SLS to aqueous inks leads to elevated conductivity up to 3.2x107 Sm-1 at maintained printability and an improved contour definition with respect to pure aqueous inks.
Naval shipbuilding was one of the most ambitious industrial undertakings of World War II. A marginal business, in 1939 employing only twelve shipyards, it expanded over the course of the war into a massive network of shipbuilding firms, engineering works, steel mills, and specialty producers that built the world's largest fleet. At its peak in 1944, warship building employed one million shipyard workers, a million others in collateral industries, and consumed one-fifth of the nation's steel output in the construction of aircraft carriers, battleships, cruisers, destroyers, and thousands of smaller combatants.
Practice guidelines for the care of post-stroke patients clearly state that all patients must be assessed for the presence of depression. However, several factors can complicate the diagnosis of depression following stroke: first, language disorders due to decreased level of consciousness or fluent (Wernicke's) aphasia with comprehension deficit. Although the pathogenesis of post-stroke depression (PSD) remains unknown, a biopsychosocial approach to treatment is probably the most appropriate. The physical treatments include antidepressants and electroconvulsive therapy. Most studies have failed to find a difference in recovery when comparing patients given antidepressants versus those given placebo. Six studies have found that patients with post-stroke depression have increased mortality compared with non-depressed stroke patients. As PSD has been associated with impaired recovery and increased mortality, consideration of a preventive intervention among non-depressed patients should be discussed with the patient, the family, and the treating physician.