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"Janssen, R. M. J."
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Full-Array Noise Performance of Deployment-Grade SuperSpec mm-Wave On-Chip Spectrometers
SuperSpec is an on-chip filter bank spectrometer designed for wideband moderate-resolution spectroscopy at millimeter wavelengths, employing TiN kinetic inductance detectors. SuperSpec technology will enable large-format spectroscopic integral field units suitable for high-redshift line intensity mapping and multi-object spectrographs. In previous results, we have demonstrated noise performance in individual detectors suitable for photon noise-limited ground-based observations at excellent mm-wave sites. In these proceedings, we present the noise performance of a full
R
∼
275
spectrometer measured using deployment-ready RF hardware and software. We report typical noise equivalent powers through the full device of
∼
3
×
10
-
16
W
Hz
-
1
/
2
at expected sky loadings, which are photon noise dominated. Based on these results, we plan to deploy a six-spectrometer demonstration instrument to the Large Millimeter Telescope in early 2020.
Journal Article
Ancillary investigations to diagnose parkinsonism: a prospective clinical study
Various ancillary investigations can assist clinicians in the differential diagnosis of patients with parkinsonism. It is unknown which test offers greatest diagnostic value in clinical practice. We included 156 consecutive patients with parkinsonism, but with an initially uncertain diagnosis. At baseline, all patients underwent extensive clinical testing and the following ancillary investigations: brain magnetic resonance imaging (MRI);
123
I-iodobenzamide single photon-emission computed tomography (IBZM-SPECT); analysis of cerebrospinal fluid (CSF); and anal sphincter electromyography (EMG). The final diagnosis was established after 3-year follow-up by two movement disorder specialists, according to international consensus criteria. We determined the diagnostic value by comparing the baseline clinical parameters and ancillary studies with the final diagnosis. Out of a potential 138 parameters, univariate analysis identified 35 parameters that discriminated Parkinson’s disease (PD,
n
= 62) and atypical parkinsonism (AP,
n
= 94), with AUC of 0.55–0.81. Stepwise logistic regression showed that the combination of tandem gait, axial UPDRS subscore, slow saccadic eye movements and dysphagia yielded an AUC of 0.93, adjusted for optimism. The combination of tandem gait and axial UDPRS subscore yielded an AUC of 0.90. None of the ancillary investigations alone or in combination with clinical testing improved this clinically based diagnostic accuracy, not even in a subgroup of patients with the greatest diagnostic uncertainty at baseline. Our study demonstrates that a comprehensive set of clinical tests provides good accuracy to differentiate PD from AP. Our results also suggest that routine MRI, IBZM-SPECT, CSF analysis and anal sphincter EMG do not improve this diagnostic accuracy. Future work should evaluate the possible diagnostic value of more advanced diagnostic tests.
Journal Article
Measuring the Interstellar Medium Content of Nearby, Luminous, Type 1 and Type 2 QSOs through CO and C ii
We present observations of CO(1–0) and CO(2–1) lines from the Institut de radioastronomie millimétrique 30 m telescope toward 20 nearby, optically luminous type 2 quasars (QSO2s) and observations of the [C ii] 158 μm line from the Stratospheric Observatory for Infrared Astronomy for five QSO2s in the CO sample and five type 1 quasars (QSO1s). In the traditional evolutionary scenario explaining different types of QSOs, obscured QSO2s emerge from gas-rich mergers observed as luminous infrared galaxies (LIRGs) and then turn into unobscured QSO1s as the black holes clear out the obscuring material in a blowout phase. We test the validity of this theoretical prediction by comparing the gas fractions and star formation efficiencies among LIRGs and QSOs. We find that CO luminosity, CO-derived gas masses, and gas fractions in QSO1s are consistent with those estimated for QSO2s, while LIRGs exhibit a closer resemblance to QSO2s in terms of CO-derived gas masses and gas fractions. Comparisons between [C ii] luminosity and star formation tracers such as the CO and infrared luminosity imply additional sources of [C ii] emission in QSO1s likely tracing neutral atomic or ionized gas with the caveat of a small sample size. All three types of galaxies have statistically indistinguishable distributions of star formation efficiency. Our results are consistent with part of the evolutionary scenario where nearby QSO2s could emerge from LIRGs, but they may not be the precursors of nearby QSO1s.
Journal Article
Design of the Kinetic Inductance Detector Based Focal Plane Assembly for the Terahertz Intensity Mapper
We report on the kinetic inductance detector (KID) array focal plane assembly design for the Terahertz Intensity Mapper (TIM). Each of the 2 arrays consists of 4 wafer-sized dies (quadrants), and the overall assembly must satisfy thermal and mechanical requirements, while maintaining high optical efficiency and a suitable electromagnetic environment for the KIDs. In particular, our design manages to strictly maintain a 50
μ
m
air gap between the array and the horn block. We have prototyped and are now testing a sub-scale assembly which houses a single quadrant for characterization before integration into the full array. The initial test result shows
a
>95% yield, indicating a good performance of our TIM detector packaging design.
Journal Article
Absorber Design and Optimization of Kinetic Inductance Detectors for the Terahertz Intensity Mapper
We discuss the design and optimization of the absorber for Terahertz Intensity Mapper, a balloon-borne kinetic inductance detector spectrometer. The novel “chain-link” absorber design offers excellent performance, independent optimization for both polarizations, and robust fabrication. Electromagnetic simulations indicate in-band absorption efficiency over
∼
90
%
in both linear polarization modes. DC measurements on different film thicknesses indicate the desired sheet resistance.
Journal Article
SuperSpec: On-Chip Spectrometer Design, Characterization, and Performance
SuperSpec is an integrated, on-chip spectrometer for millimeter and sub-millimeter astronomy intended to pave the way for large-scale, multi-beam spectrometer instruments. SuperSpec is demonstrating a three beam, dual-polarization instrument for observing star formation in distant galaxies on the Large Millimeter Telescope , a 50 m telescope on Volcan Sierra Negra in Mexico. SuperSpec provides moderate resolution (
R
∼
270
-
290
) in the 1 mm atmospheric window (200–300 GHz) with a lithographically patterned filterbank on a 3.5 cm x 5.5 cm chip. The filterbank intended for deployment is implemented in niobium, fed by a lensed antenna, and using a extremely low-volume (
2.6
μ
m
3
) titanium nitride lumped element kinetic inductor detectors (LEKIDs) as the sensors. The small size of the spectrometer and inherent multiplexibility of the kinetic inductance detectors will allow the future use of SuperSpec in larger, multi-pixel/multi-object spectrometers far beyond the three-pixel spectrometer being demonstrated soon. We report the design of the spectrometer, laboratory characterization of devices for the upcoming SuperSpec deployment. This involves laboratory testing of the filterbank spectral response, and observing noise in the TiN KIDs.
Journal Article
Thermal Simulations of Temperature Excursions on the Athena X-IFU Detector Wafer from Impacts by Cosmic Rays
We present the design and implementation of a thermal model, developed in COMSOL, aiming to probe the wafer-scale thermal response arising from realistic rates and energies of cosmic rays at L2 impacting the detector wafer of Athena X-IFU. The wafer thermal model is a four-layer 2D model, where two layers represent the constituent materials (Si bulk and Si
3
N
4
membrane) and two layers represent the Au metallization layer’s phonon and electron temperatures. We base the simulation geometry on the current specifications for the X-IFU detector wafer and simulate cosmic ray impacts using a simple power injection into the Si bulk. We measure the temperature at the point of the instrument’s most central TES detector. By probing the response of the system and pulse characteristics as a function of the thermal input energy and location, we reconstruct cosmic ray pulses in Python. By utilizing this code, along with the results of the GEANT4 simulations produced for X-IFU, we produce realistic time-ordered data (TOD) of the temperature seen by the central TES, which we use to simulate the degradation of the energy resolution of the instrument in space-like conditions on this wafer. We find a degradation to the energy resolution of 7 keV X-rays of
≈
0.04 eV. By modifying wafer parameters and comparing the simulated TOD, this study is a valuable tool for probing design changes on the thermal background seen by the detectors.
Journal Article
Evaluation of a Gastrointestinal Symptoms Questionnaire
Questionnaires are widely used instruments to monitor gastrointestinal (GI) symptoms. However, few of these questionnaires have been formally evaluated. We sought to evaluate our GI symptoms questionnaire in terms of clarity and reproducibility. Primary care patients referred for open access Helicobacter pylori urea breath testing reported GI symptoms (type+severity) and demographic information by written questionnaire. In an interview, patients gave a personal description of the meaning of the GI symptoms on the questionnaire. Patients' descriptions of GI symptoms were compared with current definitions. Symptom severity scores were compared before and after, interview versus questionnaire. Of the 45 patients included, 19 (42%) described all symptoms correctly, whereas 17 (38%) described one symptom incorrectly. None of the patients made more than three mistakes. Regurgitation was the most common incorrectly described symptom (16 patients [36%]), whereas the other individual symptoms were well explained. Symptom severities before the interview, after the interview and reported by questionnaire (mean value+/-SEM) were 2.1 +/- 0.2, 2.1 +/- 0.2, and 1.5 +/- 0.2 points on a 7-point Likert scale (0-6), respectively. Mean severity reported by interview (95% CI) was 1.4 (1.3-1.5) times higher than reported by questionnaire (P < .05). In conclusion, the GI symptom questionnaire is understandable and has good reproducibility for measuring the presence of GI symptoms, although symptom severity is consistently rated higher when reported by interview.
Journal Article
Health care reform and financial crisis in the Netherlands: consequences for the financial arena of health care organizations
Over the past decade, many health care systems across the Global North have implemented elements of market mechanisms while also dealing with the consequences of the financial crisis. Although effects of these two developments have been researched separately, their combined impact on the governance of health care organizations has received less attention. The aim of this study is to understand how health care reforms and the financial crisis together shaped new roles and interactions within health care. The Netherlands – where dynamics between health care organizations and their financial stakeholders (i.e., banks and health insurers) were particularly impacted – provides an illustrative case. Through semi-structured interviews, additional document analysis and insights from institutional change theory, we show how banks intensified relationship management, increased demands on loan applications and shifted financial risks onto health care organizations, while health insurers tightened up their monitoring and accountability practices towards health care organizations. In return, health care organizations were urged to rearrange their operations and become more risk-minded. They became increasingly dependent on banks and health insurers for their existence. Moreover, with this study, we show how institutional arenas come about through both the long-term efforts of institutional agents and unpredictable implications of economic and societal crises.
Journal Article