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This paper reports on an ultra-wideband low-noise distributed amplifier (LNDA) in a transferred-substrate InP double heterojunction bipolar transistor (DHBT) technology which exhibits a uniform low-noise characteristic over a large frequency range. To obtain very high bandwidth, a distributed architecture has been chosen with cascode unit gain cells. Each unit cell consists of two cascode-connected transistors with 500 nm emitter length and ft/fmax of ~360/492 GHz, respectively. Due to optimum line-impedance matching, low common-base transistor capacitance, and low collector-current operation, the circuit exhibits a low-noise figure (NF) over a broad frequency range. A 3-dB bandwidth from 40 to 185 GHz is measured, with an NF of 8 dB within the frequency range between 75 and 105 GHz. Moreover, this circuit demonstrates the widest 3-dB bandwidth operation among all reported single-stage amplifiers with a cascode configuration. Additionally, this work has proposed that the noise sources of the InP DHBTs are largely uncorrelated. As a result, a reliable prediction can be done for the NF of ultra-wideband circuits beyond the frequency range of the measurement equipment.
This paper presents a fully digital transmitter chain from baseband to antenna, including a modulator, two truly digital (i.e. fully switched) microwave power amplifiers and a transmit/receive switch. Both, amplifier and switch monolithic microwave integrated circuits were implemented in a GaN HEMT process. The novel amplifier design provides greatly reduced complexity, needing only three voltage sources. Measurements were conducted using 5, 20, and 100 MHz wide baseband signals. Carrier frequencies cover the 900 and 2000 MHz bands. For the 5 MHz BB signal an ACLR of over 52 dB is reached, fulfilling the 3GPP specs for base station use while still maintaining a final-stage drain efficiency of 46% at 6.5 dB peak to average power ratio. Full-scale output power at 30 V supply voltage was measured to exceed 3 W at 80% drain efficiency. Further features of this digital amplifier approach include small form factor and frequency agility, making it an ideal candidate for software defined radio.
Most modern instrumental methods of analysis depend on the use of known standards of composition for calibration. Newer analytical techniques, such as the solids mass spectrometer, laser probe and, especially, the electron-probe microanalyzer have reduced the amount of a sample which can be analyzed quantitatively to a range of about 0.1 to as small as 0.00005 μg. As a corollary to these microanalytical advances, homogeneity requirements have become severe to meet analytical standards. This paper describes a continuation of the National Bureau of Standards' effort to characterize more fully existing standards as to suitability for the new microanalytical techniques. An NBS cartridge brass sample in both the wrought (NBS-1102) and chill cast forms (NBS-C1102), as well as a low-alloy steel sample (NBS-463), have been investigated by means of electron-probe micreanalysis and optical metallography. Some 17 elements are contained in the brass, while 25 elements are found in the steel. Results for 10 elements in the steel and 6 elements in the brass are presented. In the steel, iron, nickel, copper, and silicon ate essentially distributed homogeneously at micron levels, while manganese, tantalum, niobium, zirconium, sulfur, and chromium are not. In the brass, copper and zinc are distributed homogeneously at micron levels while lead, sulfur, aluminum, and silicon are not. Electron-probe micreanalyzer results indicate that both NBS-1102 and NBS-C1102 brass are suitable for use as a calibration standard for electronprobe microanalysis as well as other microsnalyticat techniques, such as the solids mass spectrometer. The results for brass have been corroborated by a number of laboratories using the electron-probe analyzer.
To evaluate whole-genome sequencing (WGS) as a molecular typing tool for MRSA outbreak investigation.
Investigation of MRSA colonization/infection in a neonatal intensive care unit (NICU) over 3 years (2014–2017).
Single-center level IV NICU.
NICU infants and healthcare workers (HCWs).
Infants were screened for MRSA using a swab of the anterior nares, axilla, and groin, initially by targeted (ring) screening, and later by universal weekly screening. Clinical cultures were collected as indicated. HCWs were screened once using swabs of the anterior nares. MRSA isolates were typed using WGS with core-genome multilocus sequence typing (cgMLST) analysis and by pulsed-field gel electrophoresis (PFGE). Colonized and infected infants and HCWs were decolonized. Control strategies included reinforcement of hand hygiene, use of contact precautions, cohorting, enhanced environmental cleaning, and remodeling of the NICU.
We identified 64 MRSA-positive infants: 53 (83%) by screening and 11 (17%) by clinical cultures. Of 85 screened HCWs, 5 (6%) were MRSA positive. WGS of MRSA isolates identified 2 large clusters (WGS groups 1 and 2), 1 small cluster (WGS group 3), and 8 unrelated isolates. PFGE failed to distinguish WGS group 2 and 3 isolates. WGS groups 1 and 2 were codistributed over time. HCW MRSA isolates were primarily in WGS group 1. New infant MRSA cases declined after implementation of the control interventions.
We identified 2 contemporaneous MRSA outbreaks alongside sporadic cases in a NICU. WGS was used to determine strain relatedness at a higher resolution than PFGE and was useful in guiding efforts to control MRSA transmission.
Post-traumatic stress disorder (PTSD) is often associated with attention allocation and emotional regulation difficulties, but the brain dynamics underlying these deficits are unknown. The emotional Stroop task (EST) is an ideal means to monitor these difficulties, because participants are asked to attend to non-emotional aspects of the stimuli. In this study, we used magnetoencephalography (MEG) and the EST to monitor attention allocation and emotional regulation during the processing of emotionally charged stimuli in combat veterans with and without PTSD.
A total of 31 veterans with PTSD and 20 without PTSD performed the EST during MEG. Three categories of stimuli were used, including combat-related, generally threatening and neutral words. MEG data were imaged in the time-frequency domain and the network dynamics were probed for differences in processing threatening and non-threatening words.
Behaviorally, veterans with PTSD were significantly slower in responding to combat-related relative to neutral and generally threatening words. Veterans without PTSD exhibited no significant differences in responding to the three different word types. Neurophysiologically, we found a significant three-way interaction between group, word type and time period across multiple brain regions. Follow-up testing indicated stronger theta-frequency (4–8 Hz) responses in the right ventral prefrontal (0.4–0.8 s) and superior temporal cortices (0.6–0.8 s) of veterans without PTSD compared with those with PTSD during the processing of combat-related words.
Our data indicated that veterans with PTSD exhibited deficits in attention allocation and emotional regulation when processing trauma cues, while those without PTSD were able to regulate emotion by directing attention away from threat.
In accordance with suggestions made by members of the Commission further consideration of the following topics is proposed:
(1)Improvement of the present plan for distribution of observations and computations relating to minor planets and comets, with special reference to those which depart considerably from their ephemerides.
(2)Designation of a central bureau to supervise any accepted plan for coordination of observations and computations. It is suggested that separate bureaus be established for Minor Planets and for Comets.
(3)Systematic investigations of the orbits of the recently discovered objects designated as minor planets: Reinmuth 1932 HA, and Delporte 1932 EA1( and other objects of similar interest.
(4)Financing of proposals (2) and (3).
(5)Standard equinoxes as proposed by Comrie (1950.0) and by Bower (1900.0).
(6)Designation of published residuals as observed residuals rather than referring to the epoch of the comparison star.
(7)Greater adherence to the convention “That the dates used in giving the osculation epochs of elements for comets and minor planets shall be the midnight following an integral Julian date which is exactly divisible by 40, and for ephemerides, divisible by 8 (or 4, etc.),” to facilitate intercomparison of ephemerides and elements.
(8)Inauguration of complete residuals of comets, similar to those of minor planets with provision for their continuation.
(9)Inclusion in astronomical telegrams of some information of a descriptive nature to indicate the accuracy of the measured position, in confirmation of previous action.
(10)Greater emphasis on accurate rather than on approximate positions, particularly in (9), or preliminary orbits.
In accordance with action taken by the Commission at the 1932 meeting of the Union, the President has taken steps to ascertain the general opinion of computers and observers in regard to the co-operation of the Nautical Almanac offices in furnishing data for the equinox of 1900. The question under discussion is that of the adoption of the standard equinox to which observations and elements should be referred, e.g. 1900, 1950, etc. The opinion is being ascertained through a questionnaire, the results of which will be reported at the meeting. In this connection Commission 4 proposes discussion of the following resolution in co-operation with Commission 20:
“That, as from 1938 January 1, the equinox used for expressing the elements of cometary orbits and for cometary ephemerides shall be that of 1950.0. Further that, as from the same date, the equinox used in giving observed positions of comets shall be that of 1950.0, unless the observer, for good reasons, used some other equinox and expressly draws attention to the equinox used.”
In view of the considerable ground covered by the Commission at its Paris meetings and the fairly complete record of the activities of institutes and observatories, etc. published in the Minutes, it has not been deemed profitable by the president to call for further reports in advance of the Stockholm meeting. At the Paris meeting it was agreed that such reports be printed independently before each meeting of the Union and that reprints of or references to the published reports be sent to the president. It is hoped that all such reports if ready will be made available before the Stockholm meeting so that they may be summarized by the representatives in attendance or by the president and recorded in the Minutes. With reference to the pronouncement at the Paris meeting “that it is eminently desirable that more attention be given to the development of accurate general perturbations and mean elements on the basis of accurate osculating elements”, the president has visited the Planeten-Institut at Frankfurt and the Rechen-Institut at Berlin and has been in correspondence with the Leningrad Institute. From these sources particularly valuable material has been received.
There do not appear to be at the present moment any problems in dynamical astronomy of which the solutions call for combined action and international organisation rather than private efforts of mathematicians. The only possible contents of a report of the commission under these circumstances would be a historical survey of the work done in the subject since the last meeting. I do not think that a review of this nature is the proper function of such a report. My conviction that the subject of dynamical astronomy does not at the present moment stand in need of international co-operation, has been strengthened by the fact that a circular letter sent to all members of the commission has elicited only two replies, one of which expressed doubt regarding the usefulness of international co-ordination of the subject, whilst the other intimated that the writer had no remarks to offer.
Obesity and type 2 diabetes lead to dramatically increased risks of atherosclerosis and CHD. Multiple mechanisms converge to promote atherosclerosis by increasing endothelial oxidative stress and up-regulating expression of pro-inflammatory molecules. Microvesicles (MV) are small ( < 1 μm) circulating particles that transport proteins and genetic material, through which they are able to mediate cell–cell communication and influence gene expression. Since MV are increased in plasma of obese, insulin-resistant and diabetic individuals, who often exhibit chronic vascular inflammation, and long-term feeding of a high-fat diet (HFD) to rats is a well-described model of obesity and insulin resistance, we hypothesised that this may be a useful model to study the impact of MV on endothelial inflammation. The number and cellular origin of MV from HFD-fed obese rats were characterised by flow cytometry. Total MV were significantly increased after feeding HFD compared to feeding chow (P< 0·001), with significantly elevated numbers of MV derived from leucocyte, endothelial and platelet compartments (P< 0·01 for each cell type). MV were isolated from plasma and their ability to induce reactive oxygen species (ROS) formation and vascular cell adhesion molecule (VCAM)-1 expression was measured in primary rat cardiac endothelial cells in vitro. MV from HFD-fed rats induced significant ROS (P< 0·001) and VCAM-1 expression (P= 0·0275), indicative of a pro-inflammatory MV phenotype in this model of obesity. These findings confirm that this is a useful model to further study the mechanisms by which diet can influence MV release and subsequent effects on cardio-metabolic health.
Primary school years seem to represent a critical period for the development of overweight and obesity. However, only a few studies have analysed the prospective relationship between dietary patterns and weight status in children. The aims of the present study were to identify dietary patterns at the beginning of and during the primary school period and to examine their relevance to the development of body composition. Nutritional and anthropometric data from 371 participants of the Dortmund Nutritional and Longitudinally Designed (DONALD) Study at the beginning (ages 6 and 7 years) and end (ages 10 and 11 years) of the primary school period were used. Principal component analyses (PCA) were conducted to identify dietary patterns, which were regressed on changes in BMI and fat mass index (FMI) between ages 6 and 7 years and ages 10 and 11 years. Reduced rank regression (RRR) was used to directly extract patterns explaining variation in changes in BMI and FMI between ages 6 and 7 years and ages 10 and 11 years. PCA yielded interpretable patterns of dietary changes at the beginning of and during the primary school period, which were not related to changes in body composition. Conversely, RRR allowed identifying predictive patterns: higher baseline intakes of white bread and lower baseline intakes of whole-grain products as well as increases in the consumption of savoury snacks, sausages and cheese during primary school years independently predicted increases in BMI and FMI during the primary school period. In conclusion, selection of unfavourable carbohydrate sources at the beginning of the primary school period and increases in the consumption of processed savoury foods during primary school years may adversely affect the development of body composition during the course of primary school.
This paper reports on digital transmitter architecture for the 450 MHz band using an envelope delta-sigma modulator realized in CMOS and a voltage-mode class-S (VMCS) power amplifier (PA) based on GaN monolithic microwave integrated circuits (MMICs). The class-S PA is characterized for narrowband single-tone signals and a single- as well as a four-carrier downlink wideband code division multiple access (WCDMA) signal with a peak-to-average power ratio of 7.5 dB. Using single-tone excitation the PA shows a maximum drain efficiency of 86% and a peak output power of 4.4 W. At 6 and 10 dB back-off, 59 and 36% efficiency are achieved, respectively. With the single- and four-carrier WCDMA input signals maximum drain efficiencies of 64 and 53% are reached, respectively, and peak output power is 0.7 W. The adjacent channel leakage ratio shows values of about −34 dBc (5 MHz) and −38 dBc (10 MHz) for single-carrier WCDMA excitation. This is the first complete VMCS PA chain characterized with standard communication signals.
A very flexible maskless technique for thin film hybrid formation has been developed. Lay outs are transferred directly from work stations to laser controls. Openings in ceramic substrates are achieved through laser cutting, and chips are embedded to give a common chip-to-substrate surface, flat to within 2 μm. Dielectric layers of polyimide are formed by spin on techniques and are then laser structured for via hole formation.
Interconnections of the embedded chips are generated by laser direct writing of thin copper lines from copper formate, followed by chemical copper deposition. Chemical pretreatments of the aluminum contact pads allow for reasonable chip contacting with these methods. Electrical measurements on the dc line conductivity and the high frequency behaviour of these interconnections have also been performed.
Sputter deposited MnSb thin films were annealed utilizing KrF excimer laser pulses (16ns), and the resulting structural and magnetic changes investigated. These changes are compared to those observed when the samples are subjected to isothermal and rapid thermal annealing treatments. Isothermal and rapid thermal annealing induce significant lateral grain growth, whereas the laser treatment produces vertical grain size refinement with no appreciable lateral growth. Annealing is shown to increase the hexagonal c-axis, reaching an expansion value of 7% for the laser annealed samples. This c-axis expansion has a strong influence on the magnetic properties of the thin films. Mechanisms for the c-axis expansion are discussed.
The surface spin-flop and Néel transitions are examined in Fe/Cr superlattices. The surface spin-flop, originally predicted by Mills [Phys. Rev. Lett. 20, 18 (1968)], is observed in Fe/Cr(211) superlattices with antiferromagnetic interlayer coupling and uniaxial in-plane anisotropy. The Néel transition (TN) of Cr is observed in Fe/Cr(001) superlattices, for which the onset of antiferromagnetism is at a thickness tCr of 42Å. The bulk value of TN is approached asymptotically as tCr increases and is characterized by a three-dimensional shift exponent. These TN results are attributed to finite-size effects and spin-frustration near rough Fe-Cr interfaces.