Primary graft dysfunction (PGD) is one of the most common causes of early death after orthotopic heart transplantation. Mechanical circulatory support devices are required for severe forms of PGD. ...Venoarterial extracorporeal membrane oxygenation (VA-ECMO) and temporary ventricular assist device (VAD) support have both been reported to be useful for severe PGD.
Between January 2007 and December 2015, 597 patients received a heart transplant at our center. Of those, severe PGD developed in 44 patients (7.4%), and they received a continuous-flow external VAD (n = 17) or VA-ECMO (n = 27) support within 24 hours after transplant. We compared early and late outcomes between groups.
Baseline characteristics were similar between groups. Implantation of the temporary VAD required longer cardiopulmonary bypass time compared with VA-ECMO (323 ± 86 minutes vs 216 ± 65 minutes, p < 0.0001). Patients who received a VAD were more likely to have longer support time (14 ± 17 days vs 5.2 ± 3.9 days, p = 0.011), a higher incidence of major bleeding requiring chest reexploration (77% vs 30%, p = 0.0047), and a higher incidence of renal failure requiring renal replacement therapy (53% vs 11%, p = 0.0045) after surgery. Overall hospital mortality was 27%. In-hospital mortality for VAD and VA-ECMO patients were 41% and 19%, respectively (p = 0.16). Ten patients (59%) were weaned from VAD support, and 24 (89%) were weaned from VA-ECMO support after adequate graft function recovery (p = 0.03). The 3-year post-transplant survival was 41% in the VAD group and 66% in the VA-ECMO group (p = 0.13).
For severe PGD, support with VA-ECMO appears to result in better clinical outcomes compared with VAD.
This article presents a physical unclonable function (PUF) exploiting nonlinear behaviors of bistable rings (BRs), feed-forward path, and lightweight secure architecture. To evaluate the resistance ...against modeling attacks based on contemporary machine learning (ML) techniques, the proposed PUF has been implemented on a 28 nm low-cost field programmable gate array (FPGA) device. One PUF with 64-bit challenge and 32-bit response only requires 2,144 look-up tables (LUTs) of hardware resource. Much bigger and more secure PUFs can also be easily built thanks to the lightweight and scalable characteristics. Experimental data shows that the proposed extensive PUF has enhanced ML attack resistance significantly better than individual BR, feed-forward, or XOR PUFs. It is infeasible for a support vector machine (SVM) to predict responses from the proposed PUF, which makes it one of the most promising candidates for extensive PUFs. Statistical analysis also delivers 48.31% of uniqueness and 98.15% of reliability, respectively. KCI Citation Count: 0
Right heart failure (RHF) is an unresolved issue during continuous-flow left ventricular assist device (LVAD) support. Little is known about the incidence and clinical significance of late RHF during ...LVAD support.
Between May 2004 and December 2013, 336 patients underwent continuous-flow LVAD implantation. Of these, 293 patients (87%) discharged with isolated LVAD support were included in this study. Late RHF was defined as HF requiring re-admission and medical or surgical intervention after initial surgery.
Late RHF occurred in 33 patients (11%) at a median of 99 days after discharge (range 19 to 1,357 days). Freedom from late RHF rates were 87%, 84% and 79% at 1, 2 and 3 years, respectively. RHF recurred in 15 patients. Three patients required right ventricular assist device insertion. Univariable Cox proportional hazards regression model showed diabetes mellitus (HR 2.05, 95% CI 1.03 to 4.06, p = 0.04), body mass index >29 (HR 2.47, 95% CI 1.24 to 4.94, p = 0.01) and blood urea nitrogen level >41 mg/dl (HR 2.19; 95% CI 1.10 to 4.36; p = 0.025) as significant predictors for late RHF. Estimated on-device survival rates at 2 years were 73% in the RHF group and 82% in the non-RHF group (p = 0.20). However, overall survival at 2 years was significantly worse in patients who developed late RHF (60% vs 85%, p = 0.016). This reduction was mostly attributed to worse overall outcomes in the bridge-to-transplant (BTT) population.
Late RHF is common after continuous-flow LVAD implantation, but does not affect survival during LVAD support. However, it is associated with worse overall outcomes in the BTT population.
This letter proposes a downlink multiple-input multiple-output (MIMO) non-orthogonal multiple access technique that mitigates multi-cell interference (MCI) at cell-edge users, regardless of the ...number of interfering cells, thereby improving the spectral efficiency. This technique employs specific receive beamforming vectors at the cell-edge users in clusters to minimize the MCI. Based on the receive beamforming vectors adopted by the cell-edge users, the transmit beamforming vectors for a base station (BS) and the receive beamforming vectors for cell-center users are designed to eliminate the inter-cluster interference and maximize the spectral efficiency. As each user can directly obtain its own receive beamforming vector, this technique does not require channel feedback from the users to a BS to design the receive beamforming vectors, thereby reducing the system overhead. We also derive the upper bound of the average sum rate achievable using the proposed technique. Finally, we demonstrate through simulations that the proposed technique achieves a better sum rate performance than the existing schemes and that the derived upper bound is valid.
Protected areas (PAs) play a vital role in environmental conservation, particularly in Asian countries. Numerous studies were conducted on PAs in Nepal. We analyzed 864 papers from the Web of Science ...database using two visualization tools: VOSviewer and CiteSpace. This study identified the most influential journals, institutions, countries, and regions. In addition, we investigated the changing trend of research hotspots on PAs in Nepal. Keyword mapping was conducted for each type of PA and their differences were compared. We found that the research hotspots are changing with the shifting of conservation policies in Nepal. We suggest conducting more predictive studies on the future development of PAs. Currently, PA research is mainly conducted in traditional disciplines, but with the impact of climate change and the consequent increase in its negative impacts, academic contributions from other disciplines are expected to increase much more. We found that there was a shift in research power in countries and regions. We also detected an imbalanced distribution in which “protected areas” and “national parks” have been studied the most. Only 12 publications were about the hunting reserve, despite its importance to snow leopard conservation and economic significance to the buffer zone communities.
This paper presents a circuit implemen-tation of White Rabbit (WR) protocol over 1000BASE-T technology. It synchronizes the clocks of the master and slave devices with the accuracy less than 100 ps ...(peak-to-peak clock skew). The proposed implementation provides a cost-effective solution for distributed and synchronized applications in the future since it works on gigabit Ethernet using copper media without any extra hardware resources. To achieve the high accuracy, a clock synthesis circuit using a mixed-mode clock manager (MMCM) inside a commercial FPGA and a frequency transfer strategy based on Synchronous Ethernet (SyncE) have been implemented. Measurement results show that the WR slave maintains the shared timing with the clock skew between -50.27 ps and 47.83 ps for 12 days over a simple test network. KCI Citation Count: 0
In this paper, we present self-interference (SI) cancellation techniques in the digital domain for in-band full-duplex systems employing orthogonal frequency division multiple access (OFDMA) in the ...downlink (DL) and single-carrier frequency division multiple access (SC-FDMA) in the uplink (UL), as in the long-term evolution (LTE) system. The proposed techniques use UL subcarrier nulling to accurately estimate SI channels without any UL interference. In addition, by exploiting the structures of the transmitter imperfection and the known or estimated parameters associated with the imperfection, the techniques can further improve the accuracy of SI channel estimation. We also analytically derive the lower bound of the mean square error (MSE) performance and the upper bound of the signal-to-interference-plus-noise ratio (SINR) performance for the techniques, and show that the performance of the techniques are close to the bounds. Furthermore, by utilizing the SI channel estimates and the nonlinear signal components of the SI caused by the imperfection to effectively eliminate the SI, the proposed techniques can achieve SINR performance very close to the one in perfect SI cancellation. Finally, because the SI channel estimation of the proposed techniques is performed in the time domain, the techniques do not require symbol time alignment between SI and UL symbols.
Abstract Objectives Pulmonary hypertension is often considered a contraindication to orthotopic heart transplantation. Left ventricular assist device support may improve pulmonary hypertension by ...unloading the left ventricle, making patients eligible for transplantation. We sought to investigate the effect of continuous-flow left ventricular assist device support on pulmonary hypertension and compare post-transplantation outcomes in patients with preexisting pulmonary hypertension. Methods Between March 2004 and December 2013, 256 potential orthotopic heart transplantation candidates underwent continuous-flow left ventricular assist device implantation at Columbia University. Preimplantation right heart catheterization data were available for 227 patients. Patients were divided into 2 groups on the basis of preimplantation pulmonary vascular resistance: low (<5 Wood units) (n = 182) and high (≥5 Wood units) (n = 45). Postimplantation and post-transplantation outcomes were compared between the groups. Results Pulmonary vascular resistance in the high resistance group decreased significantly during left ventricular assist device support ( P < .001). Post-transplantation in-hospital mortality was significantly higher in patients with high vascular resistance ( P < .05). However, 3-year survival after transplantation was similar between groups (85.0% and 79.0% for low and high vascular resistance, respectively; P = .45). Conclusions Continuous-flow left ventricular assist device therapy reduced pulmonary vascular resistance. Subsequent orthotopic heart transplantation in patients with significantly elevated pulmonary vascular resistance resulted in higher in-hospital mortality but similar 3-year survival.
This paper addresses issues with time synchronization using the IEEE 1588-2008 for distributed measurement and control systems. A practical implementation of the transparent clock is presented with ...the overall system architecture and detailed operation of each building block. To verify the submicrosecond accuracy using the implemented devices, an experimental setup that was analogous to a practical distributed system has been built. Measured results from the experiment show that the time error is limited below 30 ns for nodes that were connected by three switches. It is remarkable that the results are observed in spite of large packet queuing delays that were introduced by a traffic generator. The discussion on sources of time error that was outlined here provides technical considerations to designing IEEE 1588 systems.
There is growing concern regarding the association between pre-transplant amiodarone exposure and post-transplant adverse outcomes. We hypothesized that amiodarone use would be associated with the ...development of severe primary graft dysfunction (PGD) in a dose-dependent manner.
This was a retrospective review of 269 adult orthotopic heart transplantation (OHT) recipients at our institution between 2010 and 2014. At the time of OHT, 100 were receiving amiodarone therapy (Group 1) and 169 were not (Group 2).
Pre-OHT creatinine was higher in Group 1 (1.49 ± 0.63 vs 1.27 ± 0.68 mg/dl, p = 0.011). At time of listing, Group 1 had higher frequency of status 2 (42.0% vs 29.0%), and Group 2 had higher frequency of status 1A (20.7% vs 8.0%; p = 0.009). Severe PGD (mechanical circulatory support within 24 hours post-OHT) was significantly higher in Group 1 (20.0% vs 5.3%, p < 0.001). Pre-OHT amiodarone use was an independent risk factor for severe PGD (odds ratio OR, 6.05; 95% confidence interval CI, 2.47-14.83; p < 0.001) and in-hospital mortality (OR, 2.88; 95% CI, 1.05-7.88; p = 0.039) in multivariable analysis. Each 100-mg increase in the day-of-OHT amiodarone dose (OR, 1.55; 95% CI, 1.26-1.90) and each 18,300-mg increase in the 6-month cumulative dose (OR, 1.67; 95% CI, 1.31-2.15) was associated with increased odds of developing severe PGD (p < 0.001 for both).
Amiodarone use pre-OHT is independently associated with increased incidence of severe PGD and in-hospital mortality and linearly associated with increased incidence of severe PGD in a dose-dependent manner.
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