Design and implementation of page based distributed shared memory in distributed database systems

This project is the simulation of page based distributed shared memory originally called IVY proposed by Li in 1986[3] and then by Li and Hudak in 1989[4]. The \u27Page Based Distributed Shared Memory System\u27 consists of a collection of clients or workstations connected to a server by a Local Area Network. The server contains a shared memory segment within which the distributed database is located. The shared memory segment is divided in the form of pages and hence the name \u27Page Based Distributed Shared Memory System\u27 where each page represents a table within that distributed database. In the simplest variant, each page is present on exactly one machine. A reference to a local page is done at full memory speed. An attempt to reference a page on a different machine causes a page fault, which is trapped by the software. The software then sends a message to the remote machine, which finds the needed page and sends it to the requesting process. The fault is then restarted and can now complete, which is achieved with the help of Inter Process Communication (IPC) library. In essence, this design is similar to traditional virtual memory systems: when a process touches a nonresident page, a fault occurs and the operating system fetches the page and maps it in. The difference here is that instead of getting the page from the disk, the software gets it from another processor over the network. To the user process, however, the system looks very much like a traditional multiprocessor, with multiple processes are free to read and write the shared memory at will. All communication and synchronization is done via the memory, with no communication visible to the user process. The approach is not to share the entire address space, but only a selected portion of it, namely just those variables or data structures that needs to be used by more than one process. With respect to a distributed database system, and in this model, the shared variables represent the pages or tables within the shared memory segment. One does not think of each machine as having direct access to an ordinary memory but rather, to a collection of shared variables, giving a higher level of abstraction. This approach greatly reduces the amount of data that must be shared, but in most cases, considerable information about the shared data is available, such as their types, which helps optimize the implementation. Page-based distributed-shared memory takes a normal linear address space and allows the pages to migrate dynamically over the network on demand. Processes can access all of memory using normal read and write instructions and are not aware of when page faults or network transfers occur. Accesses to remote data are detected and protected by the memory management unit. In order to facilitate optimization, the shared variables or tables are replicated on multiple machines. Potentially, reads can be done locally without any network traffic, and writes are done using a multicopy update protocol. This protocol is widely used in distributed database system. The main purpose of this simulation is to discuss the issues in a Distributed Database System and how they can be overcome with the help of a Page Based Distributed Shared Memory System. In a Distributed Database System, multiple clients can read data from or write data to the database. The main issue in such a type of a system is achieving Consistency171. Consistency is defined as Any read to a location within the database returns the value stored by the most recent write operation to that location within the database m. Since multiple clients are trying to perform various operations on the same database, it is difficult to ensure that the requesting client gets the most recent copy of the database

Protein Expression, Characterization and Activity Comparisons of Wild Type and Mutant DUSP5 Proteins

Background The mitogen-activated protein kinases (MAPKs) pathway is critical for cellular signaling, and proteins such as phosphatases that regulate this pathway are important for normal tissue development. Based on our previous work on dual specificity phosphatase-5 (DUSP5), and its role in embryonic vascular development and disease, we hypothesized that mutations in DUSP5 will affect its function. Results In this study, we tested this hypothesis by generating full-length glutathione-S-transferase-tagged DUSP5 and serine 147 proline mutant (S147P) proteins from bacteria. Light scattering analysis, circular dichroism, enzymatic assays and molecular modeling approaches have been performed to extensively characterize the protein form and function. We demonstrate that both proteins are active and, interestingly, the S147P protein is hypoactive as compared to the DUSP5 WT protein in two distinct biochemical substrate assays. Furthermore, due to the novel positioning of the S147P mutation, we utilize computational modeling to reconstruct full-length DUSP5 and S147P to predict a possible mechanism for the reduced activity of S147P. Conclusion Taken together, this is the first evidence of the generation and characterization of an active, full-length, mutant DUSP5 protein which will facilitate future structure-function and drug development-based studies

Short Distance Repulsive Gravity as a Consequence of Non Trivial PPN Parameters β\beta and γ\gamma

We look for a graviton-dilaton theory which can predict non trivial values of the PPN parameters $\beta$ and/or $\gamma$ for a charge neutral point star, without any naked singularity. With the potential for dilaton $\phi$ set to zero, it contains one arbitrary function $\psi(\phi)$. Our requirements impose certain constraints on $\psi$, which lead to the following generic and model independent novel results: For a charge neutral point star, the gravitational force becomes repulsive at distances of the order of, but greater than, the Schwarzschild radius $r_0$. There is also no horizon for $r > r_0$. These results suggest that black holes are unlikely to form in a stellar collapse in this theory.Comment: 15 pages. Latex file. Extenisve modifications, results unchanged, but more supportive arguments provided. To appear in Phys. Lett.

Effects of rare kidney diseases on kidney failure: a longitudinal analysis of the UK National Registry of Rare Kidney Diseases (RaDaR) cohort

\ua9 2024 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 licenseBackground: Individuals with rare kidney diseases account for 5–10% of people with chronic kidney disease, but constitute more than 25% of patients receiving kidney replacement therapy. The National Registry of Rare Kidney Diseases (RaDaR) gathers longitudinal data from patients with these conditions, which we used to study disease progression and outcomes of death and kidney failure. Methods: People aged 0–96 years living with 28 types of rare kidney diseases were recruited from 108 UK renal care facilities. The primary outcomes were cumulative incidence of mortality and kidney failure in individuals with rare kidney diseases, which were calculated and compared with that of unselected patients with chronic kidney disease. Cumulative incidence and Kaplan–Meier survival estimates were calculated for the following outcomes: median age at kidney failure; median age at death; time from start of dialysis to death; and time from diagnosis to estimated glomerular filtration rate (eGFR) thresholds, allowing calculation of time from last eGFR of 75 mL/min per 1\ub773 m2 or more to first eGFR of less than 30 mL/min per 1\ub773 m2 (the therapeutic trial window). Findings: Between Jan 18, 2010, and July 25, 2022, 27 285 participants were recruited to RaDaR. Median follow-up time from diagnosis was 9\ub76 years (IQR 5\ub79–16\ub77). RaDaR participants had significantly higher 5-year cumulative incidence of kidney failure than 2\ub781 million UK patients with all-cause chronic kidney disease (28% vs 1%; p<0\ub70001), but better survival rates (standardised mortality ratio 0\ub742 [95% CI 0\ub732–0\ub752]; p<0\ub70001). Median age at kidney failure, median age at death, time from start of dialysis to death, time from diagnosis to eGFR thresholds, and therapeutic trial window all varied substantially between rare diseases. Interpretation: Patients with rare kidney diseases differ from the general population of individuals with chronic kidney disease: they have higher 5-year rates of kidney failure but higher survival than other patients with chronic kidney disease stages 3–5, and so are over-represented in the cohort of patients requiring kidney replacement therapy. Addressing unmet therapeutic need for patients with rare kidney diseases could have a large beneficial effect on long-term kidney replacement therapy demand. Funding: RaDaR is funded by the Medical Research Council, Kidney Research UK, Kidney Care UK, and the Polycystic Kidney Disease Charity

Effects of rare kidney diseases on kidney failure: a longitudinal analysis of the UK National Registry of Rare Kidney Diseases (RaDaR) cohort

Background Individuals with rare kidney diseases account for 5–10% of people with chronic kidney disease, but constitute more than 25% of patients receiving kidney replacement therapy. The National Registry of Rare Kidney Diseases (RaDaR) gathers longitudinal data from patients with these conditions, which we used to study disease progression and outcomes of death and kidney failure. Methods People aged 0–96 years living with 28 types of rare kidney diseases were recruited from 108 UK renal care facilities. The primary outcomes were cumulative incidence of mortality and kidney failure in individuals with rare kidney diseases, which were calculated and compared with that of unselected patients with chronic kidney disease. Cumulative incidence and Kaplan–Meier survival estimates were calculated for the following outcomes: median age at kidney failure; median age at death; time from start of dialysis to death; and time from diagnosis to estimated glomerular filtration rate (eGFR) thresholds, allowing calculation of time from last eGFR of 75 mL/min per 1·73 m2 or more to first eGFR of less than 30 mL/min per 1·73 m2 (the therapeutic trial window). Findings Between Jan 18, 2010, and July 25, 2022, 27 285 participants were recruited to RaDaR. Median follow-up time from diagnosis was 9·6 years (IQR 5·9–16·7). RaDaR participants had significantly higher 5-year cumulative incidence of kidney failure than 2·81 million UK patients with all-cause chronic kidney disease (28% vs 1%; p<0·0001), but better survival rates (standardised mortality ratio 0·42 [95% CI 0·32–0·52]; p<0·0001). Median age at kidney failure, median age at death, time from start of dialysis to death, time from diagnosis to eGFR thresholds, and therapeutic trial window all varied substantially between rare diseases. Interpretation Patients with rare kidney diseases differ from the general population of individuals with chronic kidney disease: they have higher 5-year rates of kidney failure but higher survival than other patients with chronic kidney disease stages 3–5, and so are over-represented in the cohort of patients requiring kidney replacement therapy. Addressing unmet therapeutic need for patients with rare kidney diseases could have a large beneficial effect on long-term kidney replacement therapy demand. Funding RaDaR is funded by the Medical Research Council, Kidney Research UK, Kidney Care UK, and the Polycystic Kidney Disease Charity

Impact of stops for road traffic accidents on the inter-hospital transport of critically ill children

Transport of critically ill children has become necessary following centralisation of paediatric specialist services. Children's Acute Transport Service (CATS) retrieves critically ill children in the Greater London area. Our teams have had to stop during these journeys to assist in road traffic accidents or ill passers-by. We undertook a review of our practice over a 3.5-year period. Our teams had to stop on 12 occasions over this period amounting to an incidence rate of 1 per 959 ambulance journeys. Although this is an infrequent occurrence, the impact on the retrieved patient and service delivery could be significant. We would like to direct the attention of transport services to this problem

Some studies on the incremental step (fatigue) test

Cylindrical specimens of AISI 304LN austenitic strainless stael and Nimonic 90 were deformed under strain cycling at room temperature by repeated application of strain blocks consisting of waveforms in which the amplitude gradually increased and then decreased. The dependence of the cyclic stress-strain (CSS) curve on the number of waveforms in the applied strain block was found to be considerably less for Nimonic 90 than for the stainless steel. The CSS curves generated using blocks having lower maximum strain amplitudes were below the CSS curves obtained using blocks having higher maximum strain amplitudes. The difference between the CSS curves generated using blocks of different maximum strain amplitudes was greater in stainless steel than in Nimonic 90 due to strain-induced martensite formation in the former

Effect of electropolishing on the room-temperature low-cycle fatigue behaviour of AISI 304LN stainless steel

The surfaces of specimens of AISI 304LN stainless steel were given different levels of finish by means of electropolishing and mechanical polishing with emery papers of different grit sizes. They were subjected to total strain-controlled low-cycle fatigue (LCF) deformation at room temperature. The cyclic stress response and the strain-life plots were recorded. As opposed to the mechanically polished specimens, the electropolished specimens displayed secondary hardening in the later stages of deformation even at low strain amplitudes. This behaviour could be attributed to increased martensite formation in the latter case because of the enhanced life. The effect of electropolishing in enhancing the LCF life was more pronounced at the lower strain amplitudes