Millimetre Wave Kinetic Inductance Parametric Amplification using Ridge Gap Waveguide

We present the design and simulation methodology of a superconducting ridge-gap waveguide (RGWG) as a potential basis for mm-wave kinetic inductance travelling wave parametric amplifiers (KI-TWPAs). A superconducting RGWG was designed using Ansys HFSS to support a quasi-TEM mode of transmission over a bandwidth of 20 to 120 GHz with its internal dimensions optimised for integration with W-band rectangular waveguide. A design of an impedance loaded travelling wave structure incorporating periodic perturbations of the ridge was described. A method to simulate the nonlinear kinetic inductance via user-defined components in Keysight's ADS was outlined, which yielded the power dependent S-parameters and parametric signal gain. A RGWG with a 30 nm NbTiN coating and 5 um conductor spacing, corresponding to a kinetic inductance fraction $\alpha \sim 60\%$ was used for the description of a KI-TWPA with 900 perturbations equivalent to a physical length 25 cm that achieved more than 10 dB of signal gain over a 75--110 GHz bandwidth via 4-wave mixing (4WM).Comment: 9 pages, 3 figures, submitted to the 19th International Workshop on Low Temperature Detectors (LTD19) Proceeding

The Impact of Surface Passivation on Kapitza Resistance at the Interface between a Semiconductor and Liquid Nitrogen

Cooling electronic devices to cryogenic temperatures (< 77 K) is crucial in various scientific and engineering domains. Efficient cooling involves the removal of heat generated from these devices through thermal contact with either a liquid cryogen or a dry cryostat cold stage. However, as these devices cool, thermal boundary resistance, also known as Kapitza resistance, hinders the heat flow across thermal interfaces, resulting in elevated device temperatures. In transistors, the presence of passivation layers like Silicon Nitride (SiN) introduces additional interfaces that further impede heat dissipation. This paper investigates the impact of passivation layer thickness on Kapitza resistance at the interface between a solid device and liquid nitrogen. The Kapitza resistance is measured using a capacitance thermometer that has been passivated with SiN layers ranging from 0 to 240 nm. We observe that Kapitza resistance increases with increasing passivation thickness.Comment: 6 pages, 5 Figure

Parametric amplification via superconducting contacts in a Ka band niobium pillbox cavity

Superconducting parametric amplifiers are commonly fabricated using planar transmission lines with a non-linear inductance provided by either Josephson junctions or the intrinsic kinetic inductance of the thin film. However, Banys et al. [1] reported non-linear behaviour in a niobium pillbox cavity, hypothesising that below Tc, the pair iris-bulk resonator would act as a superconducting contact surface exploiting a Josephson-like non-linearity. This work investigates this effect further by applying Keysight Technologies' Advanced Design System (ADS) to simulate the cavity using an equivalent circuit model that includes a user defined Josephson inductance component. The simulations show that for a resonance centred at nu0 = 30.649 GHz, when two tones (pump and signal) are injected into the cavity, mixing and parametric gain occur. The maximum achievable gain is explored when the resonator is taken to its bifurcation energy. These results are compared to cryogenic measurements where the pump and signal are provided by a Vector Network Analyzer

Parametric amplification via superconducting contacts in a Ka band niobium pillbox cavity

Superconducting parametric amplifiers are commonly fabricated using planar transmission lines with a non-linear inductance provided by either Josephson junctions or the intrinsic kinetic inductance of the thin film. However, Banys et al. [1] reported non-linear behaviour in a niobium pillbox cavity, hypothesising that below Tc, the pair iris-bulk resonator would act as a superconducting contact surface exploiting a Josephson-like non-linearity. This work investigates this effect further by applying Keysight Technologies' Advanced Design System (ADS) to simulate the cavity using an equivalent circuit model that includes a user defined Josephson inductance component. The simulations show that for a resonance centred at nu0 = 30.649 GHz, when two tones (pump and signal) are injected into the cavity, mixing and parametric gain occur. The maximum achievable gain is explored when the resonator is taken to its bifurcation energy. These results are compared to cryogenic measurements where the pump and signal are provided by a Vector Network Analyzer

Possible predicative role of electrical risk score on transcatheter aortic valve replacement outcomes in older patients. preliminary data

Background:Transcatheter aortic valve replacement (TAVR) is an effective procedure capable to change the natural history of the degenerative aortic valve stenosis. Despite the TAVR, the patients with advanced valve disease and severe myocardial damage (low flow, gradient and ejection fraction)show high mortality level. Aim of this study was toevaluate the predicative power of a noninvasive and inexpensive test obtained by means of a simple standard 12-leads electrocardiogram,known as the Electrical Risk Score (ERS). Methods: ERS was composed by seven simple ECG markers: heart rate (>75 bpm); QRS duration (>110 ms), left ventricular hypertrophy (Sokolow-Lyon criteria), delayed QRS transition zone (≥ V4), frontal QRS-T angle (>90°), long QTBazett (>450 ms for men and >460 in women) or JTBazett(330 ms for men and > 340 ms for women);long T peak to T end interval (Tp-e)( >89 ms). An ERS ≥ 4was considered high risk for all-cause or cardiovascular mortality.We calculated retrospectively the pre-procedure ERS in 40 TAVR patients after one year of follow-up. Results: In the follow up the all-cause and cardiovascular mortality were respectively 25% and 15%.None of survivors reported ERS ≥ 4,moreover, the ERS was the strongest predictor of all-cause (odd ratio 3.73, 95% CI: 1.44-9.66, p<0.05) or cardiovascular (odd ratio 3.95, 95% CI: 1.09-14.27, p<0.05) mortality.ROC curves showed that ERS had the widest significant sensitivity-specificity area under the curve (auc) predicting all-cause (auc: 0.855, p<0.05) or cardiovascular mortality (auc: 0.908, p<0.05). Conclusions:In this pivotal study, ERS resulted an useful tool to stratify the risk of mortality in one-year follow-up TAVR patients. Obviously, it is necessary to confirm these data in large prospective studies

Evaluation of efficacy and safety of new high-density dyes for chromovitrectomy

The purpose of this study is to evaluate the safety and efficacy of two novel heavy dyes for macular surgery: DoubledyneTM and TwinTM. One eye from each of 144 patients undergoing surgery for macular hole or macular pucker was included in the study. The eyes were randomly divided into two groups according to the dye used during surgery. Best correct visual acuity (BCVA), intraocular pressure (IOP) and retinal morphology assessed by ocular coherence tomography (OCT) were evaluated before and 1, 3, 6 and 12&nbsp;months after surgery. Only one surgeon performed each operation and provided a score ranging from 1 (poor) to 10 (excellent) for quality of staining and comfort in surgery. Statistical analysis was carried out with SPSS to compare parameters before and after surgery and between the two groups. No statistical differences were recorded in quality of staining (p = 0.11), in surgery comfort (p = 0.17) and total time of surgery (p = 0.44) between the two groups. BCVA statistically improved and central macular thickness (CMT) statistically decreased after surgery in both groups (p &lt; 0.05). No toxic dye-related complications or long-term ones affecting the retina were observed in either group. According to this data, although confirmation in further studies with larger populations and longer follow up is required, DoubledyneTM and TwinTM proved to be safe and effective dyes for macular surgery

Arrhythmic risk in elderly patients candidates to transcatheter aortic valve replacement. predicative role of repolarization temporal dispersion

Degenerative aortic valve stenosis (AS) is associated to ventricular arrhythmias and sudden cardiac death, as well as mental stress in specific patients. In such a context, substrate, autonomic imbalance as well as repolarization dispersion abnormalities play an undoubted role. Aim of the study was to evaluate the increase of premature ventricular contractions (PVC) and complex ventricular arrhythmias during mental stress in elderly patients candidate to the transcatheter aortic valve replacement (TAVR). In eighty-one elderly patients with AS we calculated several short-period RRand QT-derived variables at rest, during controlled breathing and during mild mental stress, the latter being represented by a mini-mental state evaluation (MMSE). All the myocardial repolarization dispersion markers worsened during mental stress (p &lt; 0.05). Furthermore, during MMSE, low frequency component of the RR variability increased significantly both as absolute power (LFRR) and normalized units (LFRRNU) (p &lt; 0.05) as well as the low-high frequency ratio (LFRR/HFRR) (p &lt; 0.05). Eventually, twenty-four (30%) and twelve (15%) patients increased significantly PVC and, respectively, complex ventricular arrhythmias during the MMSE administration. At multivariate logistic regression analysis, the standard deviation of QTend (QTesd), obtained at rest, was predictive of increased PVC (odd ratio: 1.54, 95% CI 1.14–2.08; p = 0.005) and complex ventricular arrhythmias (odd ratio: 2.31, 95% CI 1.40–3.83; p = 0.001) during MMSE. The QTesd showed the widest sensitive-specificity area under the curve for the increase of PVC (AUC: 0.699, 95% CI: 0.576–0.822, p &lt; 0.05) and complex ventricular arrhythmias (AUC: 0.801, 95% CI: 0.648–0.954, p &lt; 0.05). In elderly with AS ventricular arrhythmias worsened during a simple cognitive assessment, this events being a possible further burden on the outcome of TAVR. QTesd might be useful to identify those patients with the highest risk of ventricular arrhythmias. Whether the TAVR could led to a QTesd reduction and, hence, to a reductionof thearrhythmicburdenin thissettingofpatients isworthytobe investigated

Electrocardiographic and other noninvasive hemodynamic markers in decompensated CHF patients

cutely decompensated chronic heart failure (adCHF) is among the most important causes of in-hospital mortality. R-wave peak time (RpT) or delayed intrinsicoid deflection was proposed as a risk marker of sudden cardiac death and heart failure decompensation. Authors want to verify if QR interval or RpT, obtained from 12-lead standard ECG and during 5-min ECG recordings (II lead), could be useful to identify adCHF. At hospital admission, patients underwent 5-min ECG recordings, obtaining mean and standard deviation (SD) of the following ECG intervals: QR, QRS, QT, JT, and T peak–T end (Te). The RpT from a standard ECG was calculated. Patients were grouped by the age-stratified Januzzi NT-proBNP cut-off. A total of 140 patients with suspected adCHF were enrolled: 87 (mean age 83 ± 10, M/F 38/49) with and 53 (mean age: 83 ± 9, M/F: 23/30) without adCHF. V5-, V6- (p &lt; 0.05) RpT, and QRSD, QRSSD, QTSD, JTSD, and TeSD p &lt; 0.001 were significantly higher in the adCHF group. Multivariable logistic regression analysis demonstrated that the mean of QT (p &lt; 0.05) and Te (p &lt; 0.05) were the most reliable markers of in-hospital mortality. V6 RpT was directly related to NT-proBNP (r: 0.26, p &lt; 0.001) and inversely related to a left ventricular ejection fraction (r: 0.38, p &lt; 0.001). The intrinsicoid deflection time (obtained from V5-6 and QRSD) could be used as a possible marker of adCHF

The Impact of Surface Passivation on Kapitza Resistance at the Interface Between a Semiconductor and Liquid Nitrogen

Cooling electronic devices to cryogenic temperatures (&lt; 77 K) is crucial in various scientific and engineering domains. Efficient cooling involves the removal of heat generated from these devices through thermal contact with either a liquid cryogen or a dry cryostat cold stage. However, as these devices cool, thermal boundary resistance, also known as Kapitza resistance, hinders the heat flow across thermal interfaces, resulting in elevated device temperatures. In transistors, the presence of passivation layers like silicon nitride (SiN) introduces additional interfaces that further impede heat dissipation. This paper investigates the impact of passivation layer thickness on Kapitza resistance at the interface between a solid device and liquid nitrogen. The Kapitza resistance is measured using a capacitance thermometer that has been passivated with SiN layers ranging from 0 to 240 nm. We observe that Kapitza resistance increases with increasing passivation thickness.</p

Aniridia Associated with Lens Coloboma and Secondary Glaucoma Treated with Transcorneal Argon Laser Ciliary Body Photocoagulation: A Case Report

Purpose: The aim of this study is to describe the management of cataract and refractory glaucoma in a case of congenital aniridia (AN)-1. Methods: In an 18-year-old female patient affected by congenital AN, bilateral coloboma of the zonula and lens, cataract and glaucoma, pars plana vitrectomy, cataract extraction and subsequent transcorneal ciliary body argon laser photocoagulation were performed. Results: Five years after laser treatment, the best-corrected visual acuity was 20/50 and the intraocular pressure was stable at 18 mm Hg with topical pharmacological management consisting of timolol 0.5% and latanoprost 0.005%. Conclusions: From our experience, transcorneal ciliary body photocoagulation after cataract extraction and vitrectomy could be a useful technique to manage high ocular pressure in eyes affected by congenital AN