Distributed Timestamp Mechanism Based on Verifiable Delay Functions

In the data communication system,the real-time information interaction of communication device increases the risk of privacy sensitive data being tam-pered with.Therefore,maintaining data security is one of the most important issues in network data communication.Because the timestamp is the most impor-tant way to authenticate data in information interaction,it is very necessary to pro-vide timestamp service in the data communication system.However,the existing centralized timestamp mechanism is difficult to provide credible timestamp ser-vice,and users can conspire with timestamping servers to forge timestamps.Therefore,this paper designs a distributed timestamp mechanism based on contin-uous verifiable delay functions.It utilizes multiple independent timestamp servers to provide timestamp services in a distributed model and appends the timestamp to the data once the data is generated.Thus,it can prove that the data already exists at a certain time and ensure the accuracy of the timestamp.Moreover,a digital blind signature based on elliptic curve cryptography is utilized to solve the problem of timestamp forgery in timestamp service.Finally,the security ana-lysis of the scheme ensures the data security of data communication system and the concurrency rate of timestamp.The experimental results also show that the scheme greatly improves the efficiency of digital signatures.

Perioperative risk factors associated with delayed graft function following deceased donor kidney transplantation:A retrospective,single center study

BACKGROUND There is an abundant need to increase the availability of deceased donor kidney transplantation(DDKT)to address the high incidence of kidney failure.Challenges exist in the utilization of higher risk donor organs into what appears to be increasingly complex recipients;thus the identification of modifiable risk factors associated with poor outcomes is paramount.AIM To identify risk factors associated with delayed graft function(DGF).METHODS Consecutive adults undergoing DDKT between January 2016 and July 2017 were identified with a study population of 294 patients.The primary outcome was the occurrence of DGF.RESULTS The incidence of DGF was 27%.Under logistic regression,eight independent risk factors for DGF were identified including recipient body mass index≥30 kg/m^(2),baseline mean arterial pressure<110 mmHg,intraoperative phenylephrine administration,cold storage time≥16 h,donation after cardiac death,donor history of coronary artery disease,donor terminal creatinine≥1.9 mg/dL,and a hypothermic machine perfusion(HMP)pump resistance≥0.23 mmHg/mL/min.CONCLUSION We delineate the association between DGF and recipient characteristics of preinduction mean arterial pressure below 110 mmHg,metabolic syndrome,donorspecific risk factors,HMP pump parameters,and intraoperative use of phenylephrine.

Values of Donor Serum Lipids and Calcium in Predicting Graft Function after Kidney Transplantation:A Retrospective Study

Objective Delayed graft function(DGF)and early graft loss of renal grafts are determined by the quality of the kidneys from the deceased donor.As“non-traditional”risk factors,serum biomarkers of donors,such as lipids and electrolytes,have drawn increasing attention due to their effects on the postoperative outcomes of renal grafts.This study aimed to examine the value of these serum biomarkers for prediction of renal graft function.Methods The present study consecutively collected 306 patients who underwent their first single kidney transplantation(KT)from adult deceased donors in our center from January 1,2018 to December 31,2019.The correlation between postoperative outcomes[DGF and abnormal serum creatinine(SCr)after 6 and 12 months]and risk factors of donors,including gender,age,body mass index(BMI),past histories,serum lipid biomarkers[cholesterol,triglyceride,high-density lipoprotein(HDL)and low-density lipoprotein(DL)],and serum electrolytes(calcium and sodium)were analyzed and evaluated.Results(1)Donor age and pre-existing hypertension were significantly correlated with the incidence rate of DGF and high SCr level(≥2 mg/dL)at 6 and 12 months after KT(P<0.05);(2)The donor’s BMI was significantly correlated with the incidence rate of DGF after KT(P<0.05);(3)For serum lipids,merely the low level of serum HDL of the donor was correlated with the reduced incidence rate of high SCr level at 12 months after KT[P<0.05,OR(95%CI):0.425(0.202–0.97)];(4)The serum calcium of the donor was associated with the reduced incidence rate of high SCr level at 6 and 12 months after KT[P<0.05,OR(95%CI):0.184(0.045–0.747)and P<0.05,OR(95%CI):0.114(0.014–0.948),respectively].Conclusion The serum HDL and calcium of the donor may serve as predictive factors for the postoperative outcomes of renal grafts after KT,in addition to the donor’s age,BMI and pre-existing hypertension.

Exact Solutions and Finite Time Stability of Linear Conformable Fractional Systems with Pure Delay

We study nonhomogeneous systems of linear conformable fractional differential equations with pure delay.By using new conformable delayed matrix functions and the method of variation,we obtain a representation of their solutions.As an application,we derive a finite time stability result using the representation of solutions and a norm estimation of the conformable delayedmatrix functions.The obtained results are new,and they extend and improve some existing ones.Finally,an example is presented to illustrate the validity of our theoretical results.

DYNAMICS OF NEW CLASS OF HOPFIELD NEURAL NETWORKS WITH TIME-VARYING AND DISTRIBUTED DELAYS

In this paper, we investigate the dynamics and the global exponential stability of a new class of Hopfield neural network with time-varying and distributed delays. In fact, the properties of norms and the contraction principle are adjusted to ensure the existence as well as the uniqueness of the pseudo almost periodic solution, which is also its derivative pseudo almost periodic. This results are without resorting to the theory of exponential dichotomy. Furthermore, by employing the suitable Lyapunov function, some delayindependent sufficient conditions are derived for exponential convergence. The main originality lies in the fact that spaces considered in this paper generalize the notion of periodicity and almost periodicity. Lastly, two examples are given to demonstrate the validity of the proposed theoretical results.

Blockchain-based continuous data integrity checking protocol with zero-knowledge privacy protection

The cloud computing technology has emerged,developed,and matured in recent years,consequently commercializing remote outsourcing storage services.An increasing number of companies and individuals have chosen the cloud to store their data.However,accidents,such as cloud server downtime,cloud data loss,and accidental deletion,are serious issues for some applications that need to run around the clock.For some mission and business-critical applications,the continuous availability of outsourcing storage services is also necessary to protect users'outsourced data during downtime.Nevertheless,ensuring the continuous availability of data in public cloud data integrity auditing protocols leads to data privacy issues because auditors can obtain the data content of users by a sufficient number of storage proofs.Therefore,protecting data privacy is a burning issue.In addition,existing data integrity auditing schemes that rely on semi-trusted third-party auditors have several security problems,including single points of failure and performance bottlenecks.To deal with these issues,we propose herein a blockchain-based continuous data integrity checking protocol with zero-knowledge privacy protection.We realize a concrete construction by using a verifiable delay function with high efficiency and proof of retrievability,and prove the security of the proposal in a random oracle model.The proposed construction supports dynamic updates for the outsourced data.We also design smart contracts to ensure fairness among the parties involved.Finally,we implement the protocols,and the experimental results demonstrate the efficiency of the proposed protocol.

Successful kidney transplantation from an expanded criteria donor with long-term extracorporeal membrane oxygenation treatment: A case report

BACKGROUND Due to a shortage of donor kidneys, many centers have utilized graft kidneys from brain-dead donors with expanded criteria. Kidney transplantation(KT)from donors on extracorporeal membrane oxygenation(ECMO) has been identified as a successful way of expanding donor pools. However, there are currently no guidelines or recommendations that guarantee successful KT from donors undergoing ECMO treatment. Therefore, acceptance of appropriate allografts from those donors is solely based on clinician decision.CASE SUMMARY We report a case of successful KT from a brain-dead donor supported by ECMO for the longest duration to date. A 69-year-old male received a KT from a 63-yearold brain-dead donor who had been on therapeutic ECMO treatment for the previous three weeks. The recipient experienced slow recovery of graft function after surgery but was discharged home on post-operative day 17 free from hemodialysis. Allograft function gradually improved thereafter and was comparatively acceptable up to the 12 mo follow-up, with serum creatinine level of 1.67 mg/d L.CONCLUSION This case suggests that donation even after long-term ECMO treatment could provide successful KT to suitable candidates.

Innovative immunosuppression in kidney transplantation:A challenge for unmet needs

Due to the optimal results obtained in kidney transplantation and to the lack of interest of the industries,new innovative drugs in kidney transplantation are difficult to be encountered.The best strategy to find the new drugs recently developed or under development is to search in the sections of kidney transplantation still not completely covered by the drugs on the market.These unmet needs are the prevention of delayed graft function(DGF),the protection of the graft over the long time and the desensitization of preformed anti human leukocyte antigen antibodies and the treatment of the acute antibody-mediated rejection.These needs are particularly relevant due to the expansion of some kind of kidney transplantation as transplantation from non-heart beating donor and in the case of antibody-incompatible grafts.The first are particularly exposed to DGF,the latter need a safe desensitization and a safe treatments of the antibody mediated rejections that often occur.Particular caution is needed in treating these drugs.First,they are described in very recent studies and the follow-up of their effect is of course rather short.Second,some of these drugs are still in an early phase of study,even if in well-conducted randomized controlled trials.Particular caution and a careful check need to be used in trials launched 2 or 3 years ago.Indeed,is always necessary to verify whether the study is still going on or whether and why the study itself was abandoned.

FPGA Implementation of Non-Linear Cryptography

The paper focuses on the design and Field Programmable Gate Array (FPGA) implementation of embedded system for time based dual encryption scheme with Delay Compulsion Function (DCF) and also illustrates the application of DCF in time based cryptography. Further, the strength of the time based FPGA encryption algorithm with and without using DCF is analyzed using a Nios II processor. This proposed scheme enhances the security of vital data against Brute force attack by incorporating a temporal key distribution where two different keys encrypt the data simultaneously, one being the regular key and the other being the time. The time is included using a dynamically varying number of shifts thereby allowing the system to wait for the duration and this forms the second dimension of the key. Presently, available encryption systems suffer from Brute Force attack in which all the key combinations are tried in order to find the correct key. In such a case, the time taken for breaking the key depends on the speed of the system used for cryptanalysis. The proposed system adds complexity by using dynamically varying sequence of operations, by including the time as a second dimension of the key besides minimizing the possibility of Brute Force attack and increasing the time required for cryptanalysis irrespective of the system capability. As the proposed system needs concurrent execution and real time processing, the system is implemented using Altera Stratix II FPGA and the results are presented.

The Effect of Non-Invasive Goal Directed Fluid Administration on Graft Function in Deceased Donor Renal Transplantation: A Pilot Study

Background: Non-invasive goal directed fluid therapy during deceased donor renal transplant (CRT) may reduce the incidence of delayed graft function. Plethysmograph Variability Index (PVI) has been shown to predict fluid responsiveness during surgery. This pilot study evaluated the feasibility of goal directed fluid administration protocol based upon PVI studying the incidence of delayed graft function (DGF) in renal transplant recipients. Methods: Twenty patients underwent primary CRT. The Control group received intravenous fluid (IVF) at a calculated constant rate. The Treatment group received a baseline IVF infusion throughout the surgery. PVI values greater than 13% were treated with 250 ml boluses of IVF. Primary end point was DGF;total IVF administration and urinary biomarker NGAL levels were secondary endpoints. Results: Treatment group at every time point received significantly less IVF. There was no significant difference in incidence of DGF between the groups. 2 patients in the Control group and 6 in the Treatment group developed DGF. NGAL was not associated with the group assignment or total IVF given (p < 0.2). Conclusions: The effectiveness of goal directed fluid therapy with non-invasive dynamic parameters has not been validated in renal transplant surgery and larger prospective studies are needed to determine its utility in renal transplantation.

Predictive Score Model for Delayed Graft Function Based on Easily Available Variables before Kidney Donation after Cardiac Death

Background： How to evaluate the quality of donation after cardiac transplantation in China. Hence, the aim of this study was to develop kidneys before DCD. death （DCD） kidneys has become a critical problem in kidney a simple donor risk score model to evaluate the quality of DCD Methods： A total of 543 qualified kidneys were randomized in a 2：1 manner to create the development and validation cohorts. The donor variables in the development cohort were considered as candidate univariate predictors of delayed graft function （DGF）. Multivariate logistic regression was then used to identify independent predictors of DGF with P 〈 0.05. Date from validation cohort were used to validate the donor scoring model. Results： Based on the odds ratios, eight identified variables were assigned a weighted integer; the sum of the integer was the total risk score for each kidney. The donor risk score, ranging from 0 to 28, demonstrated good discriminative power with a C-statistic of 0.790. Similar results were obtained from validation cohort with C-statistic of 0.783. Based on the obtained frequencies of DGF in relation to different risk scores, we formed tour risk categories of increasing severity （scores 04, 5 9, 10-14, and 15 28）. Conclusions： The scoring model might be a good noninvasive tool for assessing the quality of DCD kidneys before donation and potentially useful for physicians to make optimal decisions about donor organ offers.

Risk factors for delayed graft function in cardiac death donor renal transplants

Background Delayed graft function （DGF） is common in kidney transplants from organ donation after cardiac death （DCD） donors. It is associated with various factors. Determination of center-specific risk factors may help to reduce the incidence of DGF and improve the transplantation results. The aim of this study is to define risk factors of DGF after renal transplantation.

Intelligent computing networks for nonlinear influenza-A epidemic model

The differential equations having delays take paramount interest in the research community due to their fundamental role to interpret and analyze the mathematical models arising in biological studies.This study deals with the exploitation of knack of artificial intelligence-based computing paradigm for numerical treatment of the functional delay differential systems that portray the dynamics of the nonlinear influenza-A epidemic model(IA-EM)by implementation of neural network backpropagation with Levenberg-Marquardt scheme(NNBLMS).The nonlinear IA-EM represented four classes of the population dynamics including susceptible,exposed,infectious and recovered individuals.The referenced datasets for NNBLMS are assembled by employing the Adams method for sufficient large number of scenarios of nonlinear IA-EM through the variation in the infection,turnover,disease associated death and recovery rates.The arbitrary selection of training,testing as well as validation samples of dataset are utilizing by designed NNBLMS to calculate the approximate numerical solutions of the nonlinear IA-EM develop a good agreement with the reference results.The proficiency,reliability and accuracy of the designed NNBLMS are further substantiated via exhaustive simulations-based outcomes in terms of mean square error,regression index and error histogram studies.

PERIODICITY IN FUNCTIONAL DIFFERENTIAL EQUATIONS

A criterion for the existence of T-periodic solutions of functional differential equations with finite delay is established, in which the uniform boundedness of solutions has been removed from the conditions. The obtained result is the counterpart of the one recently obtained for infinite delay equations, but the conditions in this work are simplified and much easier to verify. Also, the proof has been improved to be more clear and compact.

Changes in biochemical parameters on the first day after kidney transplantation： risk factors for nosocomial infection？

Background Nosocomial infection in early post-transplantation period is a tough problem for kidney transplantation. Few reports have explored the relations between biochemical parameters and nosocomial infection in kidney transplantation. This retrospective study was carried out to describe the characteristics of nosocomial infection in the very early period of kidney transplantation and to determine the risk factors in biochemical parameters and their alterations. Methods Patients who underwent their first kidney transplantation from January 2001 to March 2009 in Beijing Chao-Yang Hospital were recruited and the nosocomial infectious episodes were collected for this study. Gender, age, donor type, delayed graft function （DGF） and biochemical parameters such as serum uric acid, lipids files and albumin on day 0 （before transplantation） and day 1 （24 hours after transplantation） and their changes were analyzed with Logistic regression models for nosocomial infection. Results A total of 405 patients （315 men and 90 women） were involved in this study. There were 80 patients experiencing 113 infection episodes and 105 strains of microorganism were indentified. In univariate analysis, there were significant differences in DGF, albumin on day 0, lipoprotein （a） （Lp（a）） on day 1, change in low density lipoprotein-cholesterol （LDL-C, day 1-day 0） and change in uric acid （day 1-day 0） between nosocomial infection patients and noninfectious patients （P 〈0.05）. In multivariate analysis, change in uric acid （day 1-day 0） （OR 5.139, 95% CI 1.176-22.465, P 〈0.05）, change in LDL-C （day 1-day 0） （OR4.179, 95% CI 1.375-12.703, P 〈0.05） and DGF （OR 14.409, 95% CI 1.603-129.522, P 〈0.05） were identified as independent risk factors for nosocomial infection in kidney transplantation. Conclusions Most nosocomial infections in early postoperative period of kidney transplantation are bacterial, especially with Gram-negative bacteria. The most common infection sites are respiratory tract, urinary tract and surgical site. DGF, decrease of LDL-C and increase of uric acid could increase the risk for nosocomial infections.

Predictive value of hypothermic machine perfusion parameters combined perfusate biomarkers in deceased donor kidney transplantation

Background:Delayed graft function(DGF)is the main cause of renal function failure after kidney transplantation.This study aims at investigating the value of hypothermic machine perfusion(HMP)parameters combined with perfusate biomarkers on predicting DGF and the time of renal function recovery after deceased donor(DD)kidney transplantation.Methods:HMP parameters,perfusate biomarkers and baseline characteristics of 113 DD kidney transplantations from January 1,2019 to August 31,2019 in the First Affiliated Hospital of Xi’an Jiaotong University were retrospectively analyzed using univariate and multivariate logistic regression analysis.Results:In this study,the DGF incidence was 17.7%(20/113);The multivariate logistic regression results showed that terminal resistance(OR:1.879,95%CI 1.145-3.56)and glutathione S-transferase(GST)(OR=1.62,95%CI 1.23-2.46)were risk factors for DGF;The Cox model analysis indicated that terminal resistance was an independent hazard factor for renal function recovery time(HR=0.823,95%CI 0.735-0.981).The model combining terminal resistance and GST(AUC=0.888,95%CI:0.842-0.933)significantly improved the DGF predictability compared with the use of terminal resistance(AUC=0.756,95%CI 0.693-0.818)or GST alone(AUC=0.729,95%CI 0.591-0.806).Conclusion:According to the factors analyzed in this study,the combination of HMP parameters and perfusate biomarkers displays a potent DGF predictive value.

PERIODIC SOLUTIONS FOR HIGHER ORDER DELAY FUNCTIONAL DIFFERENTIAL EQUATION OF NEUTRAL TYPE WITH LINEAR RESTORING TERMS

Using the theory of coincidence degree, the authors studied the existence of periodic solutions for higher order delay functional differential equations of neutral type with restoring terms and some new results for the existence of periodic solutions have been obtained.

Piecewise Spectral Collocation Method for Second Order Volterra Integro-Differential Equations with Nonvanishing Delay

In this paper,the piecewise spectral-collocation method is used to solve the second-order Volterra integral differential equation with nonvanishing delay.In this collocation method,the main discontinuity point of the solution of the equation is used to divide the partitions to overcome the disturbance of the numerical error convergence caused by the main discontinuity of the solution of the equation.Derivative approximation in the sense of integral is constructed in numerical format,and the convergence of the spectral collocation method in the sense of the L¥and L2 norm is proved by the Dirichlet formula.At the same time,the error convergence also meets the effect of spectral accuracy convergence.The numerical experimental results are given at the end also verify the correctness of the theoretically proven results.

ON PERIODIC SOLUTIONS OF FUNCTIONAL DIFFERENTIAL EQUATIONS WITH INFINITE DELAY

In this paper,using Mawhin's continuation theorem in the theory of coincidence degree,we first prove the general existence theorem of periodic solutions for F.D.Es with infinite delay:dx(t)/dt=f(t,x_t),x(t)∈R^n,which is an extension of Mawhin's existence theorem of periodic solutions of F.D.Es with finite delay.Second,as an application of it,we obtain the existence theorem of positive periodic solutions of the Lotka-Volterra equations:dx(t)/dt=x(t)(a-kx(t)-by(t)),dy(t)/dt=-cy(t)+d integral from n=0 to +∞ x(t-s)y(t-s)dμ(s)+p(t).

CONTINUITY IN FUNCTIONAL DIFFERENTIAL EQUATIONS WITH INFINITE DELAY

In this paper, we investigate the continuous dependence of solutions of the functional dif-ferential equation with infinite delay x'(t) = f(t, x_t) on initial functions. Endowing the phasespare a g-norm as well as a supremum norm. we show that if the equation satifies a mild fadingmemory dondition, then the continuity of f in respect to the topology induced by the supremumnorm can yield the continuity of solutions of the equation in respect to the topology induced bythe g-norm which is stronger than the ahead one.