Recovery of loss of packet in network using constant packet reordering

When the packet is reordered the most standard implementation of the Transmission control protocol (TCP) gives poor performance. This paper proposes a new version of the TCP which gives the high throughput when the packet reordering occurs and in another case if the packet reordering is not occurs then in that case also it is friendly to other version of the TCP. Transmission control protocol constant Packet Reordering (TCP-CPR) does not depend or rely on the duplicate acknowledgement to detect the packet loss. Instead the timer is used to maintain how long packet is transmitted. In this case timer is used to keep the track how long packets are transmitted. If acknowledgement are not received within the appropriate time then packet assume to loss because of the TCP-CPR does not depend on the duplicate acknowledgement. Packet reordering has does not effect on the performance of TCP-CPR. Through the performance of the TCP-CPR consistently better than existing mechanism that make the try to make the TCP more robust to packet reordering. In case where packets are not reordered, it’s verified that TCP-CPR maintains the same throughput as the typical implementation of TCP

Control of polymorphic transition inducing preferential enrichment

Preferential enrichment is an unusual symmetry-breaking enantiomeric resolution phenomenon that is initiated by the solvent-assisted solid-to-solid transformation of a metastable polymorphic form into a thermodynamically stable one during crystallization from the supersaturated solution of a certain kind of racemic crystals. On the basis of the proposed mechanism of preferential enrichment, both induction and inhibition of preferential enrichment were successfully achieved by controlling the mode of the polymorphic transition during crystallization either by minor molecular modification or with appropriate seed crystals. Furthermore, by inducing a desired polymorphic transition during crystallization of several α-amino acids or their cocrystals with dicarboxylic acids, which were classified as a racemic compound, preferential enrichment could also be accomplished

A comparative study of early and delayed cord clamping in term deliveries

Background: Timing of clamping of the umbilical cord has always been a debatable issue. Early cord clamping (ECC) is defined as clamping of the cord within 30 seconds of delivery of the baby and delayed cord clamping (DCC) is defined as clamping of the cord between 30 to 120 seconds of delivery. Delayed cord clamping, despite some limitations, is said to be beneficial to the neonate.  A comparative study between ECC and DCC was carried out on a select group of term pregnant women without any high-risk factor and delivering at term. Aim of the study was to compare the effects of early versus delayed cord clamping on neonates and mothers. The focus was on the neonatal haemoglobin levels and adverse effects, if any on neonates and mothers in the two groups.Methods: 100 women satisfying the inclusion/exclusion criteria were recruited for the study. They were randomly divided into two groups of 50 each. Group A underwent early cord clamping and Group B delayed cord clamping. Mothers were observed for 1 hour post-delivery for any evidence of post-partum haemorrhage. Neonates were observed for any sign of tachypnea and blood sample was sent after 72 hours of delivery for analyzing Hb, hematocrit and bilirubin of the neonate.Results: The results revealed that neonates with DCC had a higher mean Hb level of 15.02 vis-à-vis the ECC group Hb of 11.69G/dl and the difference was statistically significant. Similarly mean hematocrit of DCC group was 48.67 while the ECC group mean was 42.36, the difference again was statistically significant. There was no significant side effects or complications in both mother and newborn babies.Conclusions: It was concluded that delayed cord clamping should be practiced in otherwise non high-risk deliveries

An expedient synthesis of tetrakis (cyclopropylmethyl) methane

Synthesis of tetrakis(cyclopropylmethyl)methane, a new symmetric product has been described using the radical mediated gem-diallylation of cyclopropylmethyl xanthate as a key step and its single crystal X-ray analysis established its C2-symmetry

Di-tert-butyl N,N′-(octa­hydro­penta­lene-2,5-di­yl)dicarbamate

In the molecule of the title compound, C18H32N2O4, the central bicyclo­[3.3.0]octane (octa­hydro­penta­lene) has a rigid ring junction. Both rings of the bicyclo­[3.3.0]octane unit adopt an envelope conformation, and the flexible tert-butyl­carbamoyl side chains each have an extended conformation. Such a constrained bicyclo­[3.3.0]octane aliphatic template is of inter­est with respect to the design of novel self-assembling motifs. Mol­ecules related by c-glide symmetry are linked via inter­molecular N—H⋯O hydrogen bonds, forming a two-dimensional layer structure. Neighboring layers are weakly associated along the a axis due to the close approach of the tert-butyl­carbamoyl groups (2.55 Å)

An Adaptive Leaky-Bucket Mechanism for Traffic Management in OBS Networks

In Optical Burst Switched networks, each light path carry huge amount of traffic, path failures may damage the user application. Hence fault-tolerance becomes an important issue on these networks. Blocking probability is a key index of quality of service in Optical Burst Switched (OBS) network. The Erlang formula has been used extensively in the traffic engineering of optical communication to calculate the blocking probability. A combined preventive/reactive control scheme improves the condition of packet loss due to congestion in networks. The transmission delay and the throttling rate are the major parameters which affect the performance of the reactive control. High throttling rates are most efficient for fast congestion recovery, although sometimes resulting in underutilization of the link. A combined reactive/preventive congestion control mechanism is investigated in this paper with emphasis on the Leaky Bucket (LB) mechanism chosen for source traffic policing in computer networks. The fluid-flow model is used to analyze the performance of both buffered and un-buffered LBs. It is proposed that one LB is not sufficient to manage all the source traffic parameters. If tight control, fast reaction time and a small queuing delay are required then according to the analysis done, the proposed triple LB mechanism is an effective solution. According to the delayed congestion feedback information received from the network the LB parameters are dynamically changed. The preventive control policy is compared with the adaptive control scheme. The results show that even for large propagation delays, major performance improvements are possible by using an appropriate feedback policy

Rhenium(I) tricarbonyl complex of 5,20-bis(p-tolyl)-10,15-bis(p-methoxyphenyl)-21-selenaporphyrin: first X-ray structural characterization of metal complex of 21-selenaporphyrin

Synthesis and first structural characterization of hexa coordinated rhenium(I)tricarbonyl complex of 5,20-bis( p-tolyl)-10,15-bis(p-methoxyphenyl)-21-selenaporphyrin 3 are described. The Re(I)complex of 21-selenaporphyrin 3 was synthesized by treating free base 21-selenaporphyrin in 1,2-dichlorobenzene with Re(CO)(5)Cl at reflux for 7 h and analyzed using mass, NMR, FT-IR, UV-vis and electrochemical techniques. The first structure of metal complex of 21-selenaporphyrin was determined by X-ray single crystal analysis. The crystal structure revealed that the Re(CO)(3) coordinates to two of the three inner nitrogens and one selenium to produce compound 3. The selenophene ring bent towards the Re(I)ion and the selenium is displaced by 0.41 angstrom from the mean plane of 24-atoms to coordinate with Re(I)ion in eta(1)-fashion. The 21-selenaporphyrin is distorted in compound 3 compared to free base 21-selenaporphyrin. H-1 and C-13 NMR studies indicated that compound 3 exhibits fluxional behaviour in coordination mode of binding in solution. The compound 3 is highly stable and does not undergo decomplexation under acidic conditions. The absorption spectra showed three broad Q-bands and splitted Soret band and electrochemical studies indicated that compound 3 is stable under redox conditions