We have fabricated and characterized 10,000 and 20,440 pixel Microwave Kinetic Inductance Detector (MKID) arrays for the Dark-speckle Near-IR Energy-resolved Superconducting Spectrophotometer ...(DARKNESS) and the MKID Exoplanet Camera (MEC). These instruments are designed to sit behind adaptive optics systems with the goal of directly imaging exoplanets in a 800-1400 nm band. Previous large optical and near-IR MKID arrays were fabricated using substoichiometric titanium nitride (TiN) on a silicon substrate. These arrays, however, suffered from severe non-uniformities in the TiN critical temperature, causing resonances to shift away from their designed values and lowering usable detector yield. We have begun fabricating DARKNESS and MEC arrays using platinum silicide (PtSi) on sapphire instead of TiN. Not only do these arrays have much higher uniformity than the TiN arrays, resulting in higher pixel yields, they have demonstrated better spectral resolution than TiN MKIDs of similar design. PtSi MKIDs also do not display the hot pixel effects seen when illuminating TiN on silicon MKIDs with photons with wavelengths shorter than 1 µm.
•We evaluated the potential of radiomics and machine leaning on small data samples.•Training predictive models is challenging when small data samples are available.•Small proprietary samples may be ...integrated with larger publicly available cases.•Predictive performances were evaluated on each sample and on the merged one.•Inter-sample cross validation is feasible when samples have similar composition.
Predictive models based on radiomics and machine-learning (ML) need large and annotated datasets for training, often difficult to collect. We designed an operative pipeline for model training to exploit data already available to the scientific community. The aim of this work was to explore the capability of radiomic features in predicting tumor histology and stage in patients with non-small cell lung cancer (NSCLC).
We analyzed the radiotherapy planning thoracic CT scans of a proprietary sample of 47 subjects (L-RT) and integrated this dataset with a publicly available set of 130 patients from the MAASTRO NSCLC collection (Lung1). We implemented intra- and inter-sample cross-validation strategies (CV) for evaluating the ML predictive model performances with not so large datasets.
We carried out two classification tasks: histology classification (3 classes) and overall stage classification (two classes: stage I and II). In the first task, the best performance was obtained by a Random Forest classifier, once the analysis has been restricted to stage I and II tumors of the Lung1 and L-RT merged dataset (AUC = 0.72 ± 0.11). For the overall stage classification, the best results were obtained when training on Lung1 and testing of L-RT dataset (AUC = 0.72 ± 0.04 for Random Forest and AUC = 0.84 ± 0.03 for linear-kernel Support Vector Machine).
According to the classification task to be accomplished and to the heterogeneity of the available dataset(s), different CV strategies have to be explored and compared to make a robust assessment of the potential of a predictive model based on radiomics and ML.
In recent years many papers about diagnostic applications of diffusion tensor imaging (DTI) have been published. This is because DTI allows to evaluate
in vivo
and in a non-invasive way the process ...of diffusion of water molecules in biological tissues. However, the simplified description of the diffusion process assumed in DTI does not permit to completely map the complex underlying cellular components and structures, which hinder and restrict the diffusion of water molecules. These limitations can be partially overcome by means of diffusion kurtosis imaging (DKI). The aim of this paper is the description of the theory of DKI, a new topic of growing interest in radiology. DKI is a higher order diffusion model that is a straightforward extension of the DTI model. Here, we analyze the physics underlying this method, we report our MRI acquisition protocol with the preprocessing pipeline used and the DKI parametric maps obtained on a 1.5 T scanner, and we review the most relevant clinical applications of this technique in various neurological diseases.
Search for Optical Pulsation in M82 X-2 Collura, G.; Strader, P.; Meeker, S. R. ...
The Astrophysical journal,
11/2017, Letnik:
850, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We report on a search for optical pulsation from M82 X-2 over a range of periods. M82 X-2 is an X-ray pulsar with a 1.37s average spin period and a 2.5 day sinusoidal modulation. The observations ...were done with the ARray Camera for Optical to Near-IR Spectrophotometry at the 200 inch Hale telescope at the Palomar Observatory. We performed H test and χ2 statistical analysis. No significant optical pulsations were found in the wavelength range of 3000-11000 with a pulsation period between 1.36262 and 1.37462 s. We found an upper limit on pulsed emission in the 4000-8000 wavelength range to be fainter than ∼20.5 magAB, corresponding to ∼23 Jy.
Pressurized rf cavities in ionizing beams Freemire, B.; Tollestrup, A. V.; Yonehara, K. ...
Physical review. Accelerators and beams,
06/2016, Letnik:
19, Številka:
6
Journal Article
Recenzirano
Odprti dostop
A muon collider or Higgs factory requires significant reduction of the six dimensional emittance of the beam prior to acceleration. One method to accomplish this involves building a cooling channel ...using high pressure gas filled radio frequency cavities. The performance of such a cavity when subjected to an intense particle beam must be investigated before this technology can be validated. To this end, a high pressure gas filled radio frequency (rf) test cell was built and placed in a 400 MeV beam line from the Fermilab linac to study the plasma evolution and its effect on the cavity. Hydrogen, deuterium, helium and nitrogen gases were studied. Additionally, sulfur hexafluoride and dry air were used as dopants to aid in the removal of plasma electrons. Measurements were made using a variety of beam intensities, gas pressures, dopant concentrations, and cavity rf electric fields, both with and without a 3 T external solenoidal magnetic field. Energy dissipation per electron-ion pair, electron-ion recombination rates, ion-ion recombination rates, and electron attachment times to SF6 and O2 were measured.
OBJECTIVE
To detect the different extent of renal parenchymal involvement in primary vesico‐ureteric reflux (VUR), and to evaluate the relationship between VUR grade, patient age and different ...patterns of parenchymal damage.
PATIENTS AND METHODS
This blinded retrospective study included 197 consecutive children (mean age 4.26 years, range 1 month to 13 years) with primary VUR detected by voiding cysto‐urethrography (VCUG), 99mTc‐dimercaptosuccinic acid (DMSA; 120 MBq/1.73 m2) renal scintigraphy, with scanning for 3 h after intravenous injection. An abnormal DMSA scan was classified into three subtypes: cortical defects as a single scar (SS), multiple cortical scarring (MS) and diffuse reduced uptake with small renal size. Renal absolute uptake (AU), and split‐kidney relative uptake were evaluated in refluxing and nonrefluxing renal units, and correlated with parenchymal damage and patient age. Student's t‐test and the chi‐square test were used for the statistical analysis.
RESULTS
In all, 282 refluxing and 112 nonrefluxing units were assessed. Renal damage was detected in 188 of 282 units with VUR (67%) and in 18 of 112 (16%) contralateral nonrefluxing kidneys. The mean AU was 18.7% in kidneys with VUR and 29% in nonrefluxing units (P < 0.001). The mean (sd) AU decreased from lower to higher grades of VUR, i.e. grade 0 VUR (group A), 28.97 (9.71); grade 1–3 (group B), 21.28 (8.33); grade 4–5 (group C), 14.78 (8.02). The differences were statistically significant (A vs B, B vs C, both P < 0.001). Renal damage was differently distributed in the three groups: 69 of 109 kidneys (63%) in group C (MS prevalent), 39 of 173 (22.5%) in group B (SS prevalent) and 17 of 112 (15.2%) in group A. There was no significant difference in the distribution of renal damage subtypes in patients aged < or > 2 years (SS 19.6% vs 17.9%, MS 29.6% vs 30.1%, small size 48.2% vs 46.3%). The VUR was severe (group C) in 65% of patients aged < 2 years and in 46% aged > 2 years (chi‐square, P= 0.016).
CONCLUSIONS
VUR is commonly associated with renal damage. Age (< or > 2 years) did not significantly influence the kidney lesion subtype. Reduced parenchymal function (AU) progressively decreased with the severity of VUR. Focal MS, reduced size and relative uptake were significantly more common in severe VUR, leading to multifocal lesions and hypo‐dysplasia. Renal scarring was present in up to 15% of contralateral nonrefluxing kidneys. Severe VUR behaved differently from lesser VUR in the renal scan parenchymal uptake.
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