Cardiac transplantation: five years' activity

OBJECTIVE: To analyze the initial five years experience of the new heart transplant program of Coimbra University Hospitals. METHODS: Between November 2003 aid December 2008, 132 patients were transplanted, with a mean age of 52.0 years (range 3-71 years), of whom 98 were male (74%). Half of the patients had dilated cardiomyopathy and 33% ischemic cardiomyopathy. The mean age of donors was 31.7 years and 102 were male (77%). Donor hearts were harvested at a distance in 62% of cases. There was a gender mismatch between donor and recipient (F:M) in 19% of cases and ABO blood type disparity (not identical but compatible) in 11%. In all cases we used the technique of total transplantation with bicaval anastomosis, modified in this center. Mean ischemia time was 88.9 +/- 32.2 minutes. All patients received induction therapy with basiliximab and methylprednisolone. RESULTS: Six patients (4.5%) died within 30 days or during hospitalization, due to graft failure in four and hyperacute rejection in two. Two patients required prolonged ventilation, ten (8%) required inotropic support for more than 48 hours, and four required pacemaker implantation. Mean hospital stay was 15.6 +/- 15.2 days (median 13 days). Ninety percent of patients (116/129) were maintained on triple immunosuppressive therapy, including cyclosporine, the remainder receiving tacrolimus. In 23 patients it was necessary to change the immunosuppressive regimen due to renal and/or tumoral complications, or humoral rejection. All patients are followed regularly in the Surgical Center. Thirteen patients (10%) died late of cancer (6 patients), infection (4 patients), and pancreatitis, pulmonary hypertension and suicide (one patient each). Twenty-two patients (17%) had 25 episodes of cellular rejection (> or = 2R), with clinical consequences in only one case, and five had humoral rejection (3.9%). No patients died of late rejection, but there is evidence of mild graft vascular disease in one. Actuarial survival (Kaplan-Meier) at one and five years was 90% and 82%, respectively. CONCLUSION: In this initial series of five years we obtained results equivalent to or bette than those in centers with wider and longer experience, aided by self-correction arising from our own experience. This program has increased the rate of cardiac transplantation in Portugal to above the European average

NBTI-Generated Defects in Nanoscaled Devices: Fast Characterization Methodology and Modeling

Negative bias temperature instability (NBTI)-generated defects (GDs) have been widely observed and known to play an important role in device’s lifetime. However, its characterization and modeling in nanoscaled devices is a challenge due to their stochastic nature. The objective of this paper is to develop a fast and accurate technique for characterizing the statistical properties of NBTI aging, which can be completed in one day and thus reduce test time significantly. The fast speed comes from replacing the conventional constant voltage stress by the voltage step stress (VSS), while the accuracy comes from capturing the GDs without recovery. The key advances are twofold: first, we demonstrate that this VSS-GD technique is applicable for nanoscaled devices; second, we verify the 15 accuracy of the statistical model based on the parameters extracted from this technique against independently measured data. The proposed method provides an effective solution for GD evaluation, as required when qualifying a CMOS process

NBTI of Ge pMOSFETs: understanding defects and enabling lifetime prediction

Ge pMOSFETs are strong candidates for next technology nodes and record hole mobility has been reported for Al2O3/GeO2/Ge and HfO2/SiO2/Si-cap/Ge structures. Reliability, however, is still problematic and currently impedes the progress. Large NBTI exists in GeO2/Ge, and little is known about the defects. Si-cap/Ge device has superior reliability, but its lifetime, τ, cannot be predicted by power law extrapolation. This work demonstrates that the defects are different in Ge and Si devices. For the first time, a method is developed for Ge devices to restore the power law for NBTI kinetics, which enables τ prediction and process optimization

AC NBTI of Ge pMOSFETs: Impact of Energy Alternating Defects on Lifetime Prediction

For the first time, AC lifetime in Si-cap/Ge and GeO2/Ge pMOSFETs is investigated and it must not be predicted by the conventional DC stress method with a measurement delay. This is because the energy alternating defects are generated in Ge devices but not in Si, which introduces additional generation under DC stress

Model for resource allocation in decentralized networks using Interaction nets

This article presents the description of a model for allocating resources using Interaction Nets and a strategy for playing public goods. In the description of the model first shows the behavior of the allocation of resources towards the nodes depending on the usefulness of the network and the satisfaction of the agents. Then the generalization of the model with Interaction Nets is described, and a simulation of this behavior is made. It is found that there is an emerging behavior condition in the dynamics of the interaction when assigning resources. To test the model, the interaction of sharing the Internet in an ad hoc network is done. The interaction is shown in the general model obtained

A gastrointestinal rotavirus infection mouse model for immune modulation studies

<p>Abstract</p> <p>Background</p> <p>Rotaviruses are the single most important cause of severe diarrhea in young children worldwide. The current study was conducted to assess whether colostrum containing rotavirus-specific antibodies (Gastrogard-R^®) could protect against rotavirus infection. In addition, this illness model was used to study modulatory effects of intervention on several immune parameters after re-infection.</p> <p>Methods</p> <p>BALB/c mice were treated by gavage once daily with Gastrogard-R^®from the age of 4 to 10 days, and were inoculated with rhesus rotavirus (RRV) at 7 days of age. A secondary inoculation with epizootic-diarrhea infant-mouse (EDIM) virus was administered at 17 days of age. Disease symptoms were scored daily and viral shedding was measured in fecal samples during the post-inoculation periods. Rotavirus-specific IgM, IgG and IgG subclasses in serum, T cell proliferation and rotavirus-specific delayed-type hypersensitivity (DTH) responses were also measured.</p> <p>Results</p> <p>Primary inoculation with RRV induced a mild but consistent level of diarrhea during 3-4 days post-inoculation. All mice receiving Gastrogard-R^®were 100% protected against rotavirus-induced diarrhea. Mice receiving both RRV and EDIM inoculation had a lower faecal-viral load following EDIM inoculation then mice receiving EDIM alone or Gastrogard-R^®. Mice receiving Gastrogard-R^®however displayed an enhanced rotavirus-specific T-cell proliferation whereas rotavirus-specific antibody subtypes were not affected.</p> <p>Conclusions</p> <p>Preventing RRV-induced diarrhea by Gastrogard-R^®early in life showed a diminished protection against EDIM re-infection, but a rotavirus-specific immune response was developed including both B cell and T cell responses. In general, this intervention model can be used for studying clinical symptoms as well as the immune responses required for protection against viral re-infection.</p

A test-proven As-grown-Generation (A-G) model for predicting NBTI under use-bias

For the first time, we demonstrate that A-G model extracted from short Vg-accelerated stresses can predict both long term DC and AC NBTI under low and dynamic operation Vg. This is achieved by successfully separating non-saturating defects from the saturating ones, allowing reliable extraction of power exponents needed for long term prediction. Unlike R-D model, A-G model does not require solving differential equations for AC NBTI. This saves computation time significantly, especially for high-frequency that needs small time-step, and makes it readily implementable in SPICE-like simulators

Reliable time exponents for long term prediction of negative bias temperature instability by extrapolation

To predict the negative bias temperature instability (NBTI) towards the end of pMOSFETs’ 10 years lifetime, power-law based extrapolation is the industrial standard method. The prediction accuracy crucially depends on the accuracy of time exponents, n. The n reported by early work spreads in a wide range and varies with measurement conditions, which can lead to unacceptable errors when extrapolated to 10 years. The objective of this work is to find how to make the n extraction independent of measurement conditions. After removing the contribution from as-grown hole traps (AHT), a new method is proposed to capture the generated defects (GD) in their entirety. The n extracted by this method is around 0.2 and insensitive to measurement conditions for the four fabrication processes we tested. The model based on this method is verified by comparing its prediction with measurements. Under AC operation, the model predicts that GD can contribute to ~90% of NBTI at 10 years