Asynchronous Transfer Research Articles

Ajax GIS application for GNSS availability simulation

This paper describes an Ajax (Asynchronous JavaScript and XML) GIS (geographic information system) application for the simulation of GNSS (Global Navigation Satellite System) availability in dense urban areas. In the forthcoming GNSS environment, satellite visibility will be greatly increased owing to the integration of multiple GNSSs such as the American GPS (Global Positioning System), the Russian GLONASS (Global Navigation Satellite System), the European Union’s GALILEO, and the Japanese QZSS (Quasi-Zenith Satellite System). However, in dense urban areas, the improvements of position accuracy may be limited because obstruction of the signal by high buildings results in bad geometries and multipath effects. To evaluate the spatiotemporally varying availability of GNSS positioning, we built an estimation model that computes the number of visible satellites, the values of DOP (dilution of position), and the amount of multipath errors, according to the location and time of a user. Then, the GNSS availability components were visualized in an Ajax-based Web application that provides a desktop-like interactiveness through the asynchronous data transfer between client and server. This Web simulation shows when and where the navigation services by integrated GNSS are available or appropriate in urban canyons. As a feasibility test, we demonstrated an experimental simulation for the Shinjuku ward of Tokyo filled with skyscrapers.

187 INCREASED NUMBER OF EXPANDED BOVINE BLASTOCYSTS IN SOF AND CR1 RELATIVE TO KSOM

Assessment of morphological stage grade is a subjective procedure. Stage grade is of vital importance to, among other things, recipient synchrony for the purpose of establishing successful pregnancies. Asynchronous embryo transfer has led to decreases in pregnancy rates (Farin et al. 1995 Biol. Reprod. 52, 676–682) and has been implicated in contributing to large offspring syndrome (Young et al. 1996 Theriogenology 45, 231). Differences in embryo kinetics based on culture conditions have been well documented (Mello et al. 2005 Reprod. Fert. Dev. 17, 221 abst). Whether such differences are the result of species, breed, metabolic stress, sire effects, or separation from an in vivo environment has yet to be determined. The correlation between oxygen respiration rates and embryo morphology as well as embryo diameter in bovine embryos produced in vitro has shown promise in the development of a more objective predictor of embryo quality and perhaps pregnancy initiation (Lopes et al. 2005 Reprod. Fert. Dev. 17, 151 abst). As well, recent examination of gene expression patterns of in vitro-derived bovine embryos seems to indicate that longer periods of in vitro culture are associated with lower rates of embryo survival (Lonergan et al. 2006 Theriogenology 65, 137–152). We hypothesize that differences do exist in the number, rate, and morphological appearance of blastocysts and that these parameters are in large part based on culture conditions in vitro. The objective of this experiment was to determine the timing and distribution of blastocyst formation of in vitro-produced bovine embryos cultured in SOF8, CR18AA, and KSOM8, under a standard incubation environment. Bovine ovaries from a local abattoir were aspirated and matured for 18-22. Oocytes were fertilized with frozen-thawed Percoll-separated semen from a Holstein bull. Presumptive zygotes were vortexed to remove cumulus cells and placed into 3 different culture media in a highly humidified atmosphere containing 20% oxygen, 5% carbon dioxide, and compressed air at 38.5�C. Embryos were evaluated specifically at 168 h post-insemination (Day 7) and assigned a morphological stage grade (IETS) to determine fixed time point differences. A total of 6 complete replicates were performed. Only embryos exhibiting the presence of a blastocoel at this time were documented (early blast, mid-blast, expanded blast). At 168 h post-insemination, there were no significant differences in the total number of embryos reaching early or mid-blast stage in any of the media. However, chi-square analysis revealed an increase in the number of expanded blastocysts in SOF (n = 813) and CR1 (n = 838) treatments compared to KSOM (n = 824; P < 0.0001). Expanded blastocysts in SOF were also greater in number than in CR1 (P < 0.05). Embryo selection based on development to the expanded blastocyst stage on Day 7 may prove useful in increasing pregnancy rates, and may validate qualitative correlations based on oxygen consumption and gene expression profiles for embryos produced in vitro.

Interoperability Test Generation and Minimization for Communication Protocols Based on the Multiple Stimuli Principle

This paper presents an automatic test generation and minimization method for testing interoperability of communication protocols such as the asynchronous transfer mode/broadband integrated services digital network (ATM/B-ISDN) signaling protocol and the transmission control protocol (TCP). The method is based on a technique of composing finite-state machines (FSMs). Traditionally, the generation of inputs utilizing FSM was mostly based on sequential test scripting languages and often done manually. Each input is processed on a one-at-a-time basis, which did not allow generating complex scenarios of simultaneous inputs on several interfaces of the system under test (SUT). In practice, there exists the possibility that additional inputs have to be sent to the SUT, while the previous input is still being processed, and/or multiple inputs need to be sent to different interfaces of the SUT at the same time. Our method generates interoperability test cases dealing with these more complex situations. Moreover, it minimizes the number of increased test cases due to the multiple stimuli without jeopardizing transition coverage. Experimental results have shown that compared with the conventional methods, our test generation method generates more interoperability test cases resulting in higher transition coverage (26% higher for TCP and 12% higher for ATM signaling protocol). Also, our test minimization method reduces the interoperability test cases by about 94% in the case of the ATM signaling protocol with the same transition coverage.

Performance analysis of the IEEE 1394 serial bus

IEEE 1394 is a standard for a high performance serial bus interface. It encompasses both isochronous data transfer, which is suitable for real-time applications, and asynchronous data transfer, which is appropriate for delay-insensitive applications. This standard can be used as a basis for constructing a small-size local area network. Two queueing models are proposed for a network operating under the IEEE 1394 specification. The average waiting time in steady state of an asynchronous packet is calculated, and the effect on it due to isochronous traffic is studied. Numerical results from both analysis and simulation are presented in order to evaluate the performance of such a system.

The Broadband Access Facility

The deployment of broadband access networks will revolutionise many aspects of society in the early years of the next millennium. Manufacturers, telecommunications providers and cable television operators world-wide are investing heavily on research into networks that provide broadband multimedia services to customers. BT has developed a prototype of a full service access network that can connect customers via optical fibre, digital subscriber line or radio technologies. This paper describes the physical implementation of the prototype network and the wide range of services that it can support. This prototype network, referred to as the 'broadband access facility' is enabling BT and its partners to understand the best access architectures for a given environment through practical testing. The network now serves as an experimental platform, that can be used for communicating broadband concepts, designing operational processes, developing management solutions and testing advanced applications. The full service access networks (FSAN) initiative is a collaboration involving fourteen of the world's leading telecommunications network operators and major equipment manufacturers. Its vision is to create a shared requirements specification for access systems supporting narrowband and broadband services. This common specification will mean that broadband network components can be developed for world markets, thus raising volumes and driving down unit costs. The common system specification is based around an ATM/SDH (asynchronous transfer mode/synchronous digital hierarchy) core network, with local optical fibre distribution via an ATM PON (passive optical network). DSL (digital subscriber line) systems maximise reuse of existing copper plant. The exact DSL system used depends upon where the optical system is terminated, e.g. in the local exchange, cabinet, kerb or home. Hence this broadband access system can support a range of access architectures — this flexibility is fundamental to the consensus achieved in FSAN.

Distance Learning over ATM/SONET: The Distance Learning Environment Demonstration

A new movement in learning and communicating is underway. High bandwidth data link services are being installed throughout the country in support of evolving learning and communication needs. Early adopters are pushing the infrastructure and networks to bring high quality interactive services to the desktop. “New applications such as distance learning and interactive Internet capabilities are capturing the hearts and minds of decision-makers. A growing number of businesses and institutions are facing the challenge of finding smart, affordable network solutions” [1]. Most distance learning multimedia programs remain instructor-led mediated events. The infrastructure technology is expensive to install and most applications, especially distance learning applications, do not exploit student-centric applications. Distance learning systems integrators are quick to offer high cost instructor-centric solutions, however, the educational community is slowly moving toward low cost self-directed education-on-demand. Studies, such as the Distance Learning Environment Demonstration (DLED), offer a base study solution for legacy Ethernet local area networks (LANs), school-centric courseware management, and student-centric courses. Using commercial-off-the-shelf (COTS) PC-based hardware and software, computer-based training (CBT) courseware was either re-purposed or developed new in support of the study. Students logged into a centralized server via asynchronous transfer mode/synchronous optical network (ATM/SONET) to take different interactive multimedia courses. Individual student information was tracked and stored on the server and accessible only by the administration. The centralized courseware simplified the task of software maintenance and gave instructors and administrators direct control of the courses. The performance metrics indicated that low cost high performance COTS hardware and software can be used to develop high fidelity multimedia interactive courseware distributed over a wide area network (WAN). This study would suggest that distance learning over a high bandwidth ATM/SONET WAN was a viable solution for a remote student population.

Temporary exposure of ovine embryos to an advanced uterine environment does not affect fetal weight but alters fetal muscle development.

Embryo transfer techniques may result in fetuses that are heavier at birth and that have been described as highly muscled. The aim of this study was to investigate myogenesis in lambs derived from embryo transfer. Embryos were transferred at Day 3 (estrus = Day 0) to a 3 days-advanced uterine environment, maintained there for 3 days, recovered, and then returned to a synchronous (Day 6) uterus; these fetuses comprised the asynchronous group. Control animals were created by synchronous embryo recovery and single transfer at Day 3. Asynchronous transfer did not affect fetal weight or curved crown-rump length between 46 and 135 days of gestation. No differences were detected between groups at Days 110-135 with respect to muscle mass or protein, RNA, and DNA content. However, total muscle fiber number was significantly increased in plantaris muscles from the asynchronous groups at Day 110 and Day 125, suggestive of prolonged hyperplasia. In addition, the levels of Myf 5 protein and the secondary-to-primary fiber ratio were altered in plantaris muscle from the asynchronous group. The growth data are in contrast to previously reported findings. The results show that fetal myogenesis can be altered by very early events in embryogenesis and suggest that any inferences made solely on the basis of fetal or muscle weight may be fallacious.

Increased ovine foetal weight following transient asynchronous embryo transfer is not associated with increased placental weight at day 21 of gestation

Increased ovine foetal weight following transient asynchronous embryo transfer is not associated with increased placental weight at day 21 of gestation

VLSI common voting module for fault-tolerant TMR system in industrial system control applications

Abstract The preliminary results of research on designing a new type of VLSI voting circuitry, called the common voting module (CVM) are presented. The CVM is suitable for implementation in triple modular redundant systems for industrial process control applications operating in hazardous areas. Assembling the VLSI components with the electronic instruments, computers and actuators into fault-tolerant system, we achieve a fault-detection recovery and failure isolation far exceeding non-VLSI implementations. The fundamental idea is to design and partition the logical elements so that effective fault detection, identification of the faulty source, and synchronization can be done by a novel method, which places the detection responsibility inside the VLSI chip. The CVM allows an asynchronous data transfer between the redundant system's modules and is implemented as a Moore sequencer.

The fate of embryos transferred into the uterus.

The purpose of this study is to elucidate the fate of embryos transferred into the uterus. Implantation rates were compared between synchronous and asynchronous intrauterine embryo transfers in mice. Then transferred embryos were recovered from the uterus and examined morphologically 24 hr after transfer. Moreover, the same transfer-recovery experiments were performed after ligation of the uterus two-thirds from the uterotubal junction immediately before transfer. The implantation rate was high (58.4% per embryo, 87.5% per recipient) when blastocysts were transferred into the uteri of recipients of pseudopregnant Day 4, but it was very low (0-2.4% per embryo, 0-8.3% per recipient) when blastocysts were transferred to recipients of pseudopregnant Day 2, or two-cell embryos into recipients of pseudopregnant Days 2 and 4. When transferred embryos were recovered from the uterus 24 hr after transfer, few embryos (1.4%) were recovered in asynchronous transfers, while 66.3% of the embryos were recovered in synchronous transfers. However, from recipients in which the lower portions of uteri were ligated, embryos at more advanced stages were recovered even in asynchronous transfers. These results suggest that discharge from the uterus is one of the major causes of the low implantation rate for asynchronous transfer.

Service management on an ATM DQDB MAN

In this paper a management architecture for connection-oriented services in a Distributed Queue Dual Bus (DQDB) MAN, in which channel access is exclusively queued-arbitrated, is proposed. Use of only the asynchronous information transfer mode for the integrated transport of voice/video/data services is assumed to facilitate future integration between MANs and B-ISDNs. Using a network architecture in which there are functional blocks performing adaptation functions for connection-oriented services, the authors describe a set of management processes needed to manage the node adaption blocks, services and resources assigned to them. In the description of these processes, the ways in which network resources are requested and assigned is formalized, and a certain quality is guaranteed in the connections.

The dynamic structure of rabbit blastocyst coverings

Under physiological conditions the zona pellucida disappears in the rabbit between Day 3 and early Day 4 post coitum (p.c.) and is replaced by a new layer, the neozona. The dissolution of the zona pellucida and the formation of the neozona was investigated in three different experimental approaches, all of them characterized by non-physiological developmental conditions for the embryo: Prevention of embryo migration from the oviduct into the uterus by postcoital (48 h p.c.) tubal ligation, in vitro culture, and asynchronous embryo transfer into uteri of recipient rabbits. Embryos of age 2 1/2, 3, 4 and 4 1/2 days p.c. were cultured for 12 to 72 h. The media used for in vitro culture were supplemented with BSA, serum or with uterine secretions that were collected either synchronously or asynchronously to the developmental stage of the cultured embryos. Three-day-old embryos were transferred into uteri of pseudopregnant foster rabbits of either synchronous (Day 3) or asynchronous stages (Day 0, 2, 4, 5, 6) and were recovered 24 to 72 h after transfer. The transformation of the coverings was evaluated by light and transmission electron microscopy. The dissolution of the zona pellucida was greatly disturbed in tube-locked embryos, and in cultured embryos if standard protein supplements (BSA or serum) had been used for in vitro culture. In many cases the zona was still completely preserved after 2 or 3 days in culture, at a time when it normally would have already been replaced by the neozona in vivo. The dissolution in vitro, however, progressed incomparably better if the culture medium had been substituted with synchronous or asynchronous uterine secretions. The formation of the neozona could not be verified in cultured blastocysts. After embryo transfer, the dissolution of the zona pellucida was completed in most cases by 2 days after transfer, irrespective of the recipients' progestational stage. Present results indicate that uterine components are essential for the dissolution of the rabbit zona pellucida. These components appear to be present in the uterine cavity constitutively, i.e. independently of the uterine progestational transformation, and need not be in synchrony with the embryo's developmental stage for dissolution of the zona. Normal formation of the neozona does not take place under the non-physiological developmental conditions of in vitro culture.

Successful asynchronous embryo transfer in cattle

Japanese Black primiparous and multiparous beef cows (n=120) were selected as recipients and randomly divided into three groups (A, B, and C) of 40 recipients each. Group A received an intramuscular (i.m.) treatment of 1500 IU human chorionic gonadotropin (hCG) on day 1 (day 0=onset of estrus), while Group B received an i.m. treatment of hCG on day 6. Group C received an i.m. treatment of 5 ml saline on day 6 as a control. On day 7, frozen-thawed embryo transfer was conducted in all groups, and pregnancy was diagnosed by palpated per rectum 40–50 days after the transfer. Twelve recipients were randomly selected from each group. Plasma progesterone (P) and estradiol-17β (E2) concentrations were determined in these recipients on days 6, 7 and 14, and at the time of pregnancy diagnosis, and their ovaries were examined for a corpus luteum and follicles by palpated per rectum. The pregnancy rate in Group B was higher (67.5%, P<0.05) than the rate in Group C (45.0%) and in Group A (42.5%). The plasma P concentration on day 14 tended to be higher although not significantly in Group B than in Groups C and A. At the time of pregnancy diagnosis, the blood P concentration of pregnant recipients in Group B was higher (P<0.05) than that of those in Groups C and A. The plasma E2 concentrations on days 7 and 14 were lower (P<0.05) in Group B than in Groups C and A. These results showed that administration of hCG 6 days after estrus improved the pregnancy rate for non-surgical frozen embryo transfer 7 days after estrus by enhancing luteal function and depressing E2 secretion.

Influence of cell cycle stage at nuclear transplantation on the development in vitro of mouse embryos.

Nuclei were transplanted from embryos of mice at different stages of the 1st and 2nd cell cycle to oocytes enucleated at various times after fertilization. After transfer of pronuclei, a greater proportion of embryos developed to blastocysts if donor and recipient embryos were at the same stage of the cell cycle (synchronous transfer = 94%, asynchronous transfer = 76%). By contrast, when 2-cell blastomere nuclei were fused to the cytoplasm of enucleated zygotes, there was a significant effect of both cytoplast and karyoplast cell cycle stage on the development of the reconstituted embryos. Karyoplasts and cytoplasts derived from embryos at later stages of the cell cycle had greater potential to support development to blastocysts in vitro. It is suggested that the secretion of stage-specific messengers and the timing of nuclear membrane breakdown are the main factors causing the karyoplast and cytoplast effects, respectively.

Decreased embryonic survival of in-vitro fertilized oocytes in rats is due to retardation of preimplantation development.

Immature female rats (60-65 g) were injected with 4 i.u. PMSG on Day -2 and allocated to 3 groups. On the evening of Day 0, rats in Groups I and II were allowed to mate. Embryos were collected on Day 4 (Group I, control morulae) or Day 5 (Group II, control blastocysts) and were transferred into the oviduct or uterine horn of Day-4 pregnant recipient rats. On the transfer side of the recipients, the bursa had been peeled from around the ovary to prevent endogenous oocytes from entering the oviduct. For Group III, unmated donors were killed 65-67 h after PMSG injection. Ovulated oocytes recovered from the oviducts were fertilized in vitro and transferred 16-18 h later. Embryos developing from in-vitro fertilized (IVF) oocytes were recovered on Day 5, separated into morulae (Group IIIm) and blastocysts (Group IIIb) and transferred into Day-4 pregnant recipients similar to control embryos. Some embryos from each group were used to determine the mean number of cells/embryo. Embryo recipients were killed on Day 20. After transfer, the development of IVF oocytes was retarded compared to control embryos. IVF morulae contained significantly fewer cells/embryo than did control morulae but were able to implant and grow to fetuses, in proportions similar to controls, if transferred into the oviduct of the recipients. These results suggest that the developmental potential of rat oocytes fertilized in vitro is limited due to asynchrony between the embryo and the uterine environment at the time of implantation, rather than possible defects incurred by the oocyte during the fertilization procedure.

Survival of frozen-thawed rabbit morulae after synchronous or asynchronous transfer

Rabbit embryos at the morula stage were frozen to −35°C in the presence of 1.5 M DMSO before plunging into liquid nitrogen. After rapid thawing, 79% ( 385 486 ) presented a normal appearance with intact blastomeres and zona pellucida. The in vitro development of frozen-thawed morulae was similar to that of the controls (83 vs. 86%, P>0.05). The transfer of these morulae into the oviducts of recipients ovulating at the same time as the donors gave the highest survival (55%). Survival tended to decrease after transfer to recipients ovulating 17 or 24 h after the donors (47 and 33%, P>0.05). Our results indicate that frozen-thawed rabbit morulae need synchronous conditions in order to develop well.

Survival of rabbit embryos after synchronous or asynchronous transfer

Rabbit embryos of 2 and 16–32 cells and at late morula and blastocyst stages were collected from superovulated does and transferred directly into pseudopregnant recipients ovulated at different times. The development of the transferred embryos was determined at day 17 of pregnancy. With our tubal transfer technique a high survival rate was obtained. In synchronized recipients 68, 62 and 63% of the 2 and 16–32-cell embryos and those at late morula stage, respectively, developed into fetuses. Blastocysts could develop after transfer into the oviducts of synchronized or asynchronized (− 24 h) recipients but the survival rates were low: 21 and 24%, respectively. When the recipients and donors were asynchronized, the number of implants and fetuses was reduced. This reduction was considerable when the ovulation time difference between recipients and donors exceeded 24 h. No embryos survived in recipients ovulated 72 h after the donor.

Asynchronous embryo transfer in rabbits

Asynchronous embryo transfer in rabbits

Asynchronous embryo transfer to day-4 recipient rabbits

Asynchronous embryo transfer to day-4 recipient rabbits

Survival of porcine embryos after asynchronous transfer (41495).

AbstractForty gilts and sows were used to transfer Day 5 embryos into one uterine horn, while Day 7 embryos were transferred into the other horn, of Day 6 nonpregnant recipients (Day 0 = first day of estrus). The survival of the transferred embryos was determined on Day 11 (Expt 1) and Days 60 to 70 (Expt 2). The percentage of Day 5 and 7 embryos surviving the transfer procedures on Day 11 was not different, 42 ± 10 and 43 ± 12, respectively. However, by midgestation (Day 60) more (P < 0.001) fetuses that developed from Day 7 embryos survived than fetuses that developed from Day 5 embryos, 63 ± 8 and 8 ± 7%, respectively. These experiments indicated that the presence of embryos more advanced in development caused the demise of younger embryos sometime between Days 11 and 60 of gestation.