Bertrand equilibria and efficiency in markets for congestible network services

This paper is motivated by study of the economics of Quality of Service (QoS) of congestible services. We introduce a queueing game framework to study such problems. We consider multiple competing providers, each offering a queued service. Users are sensitive to both access price and expected delay, and pick providers with the smallest price plus delay cost. We study equilibrium of the pricing (Bertrand) game between the congestible network service providers. We establish the existence of a Nash equilibrium under some natural assumptions. We then consider a setting with multiple classes of differentiated service. Differentiated Services (DiffServ) technologies of the Internet that can provide QoS guarantees have failed to catch on, primarily due to economic impediments. Each provider is now modeled as operating a multi-class queue. We provide sufficient conditions for the existence of a Nash equilibrium in the Bertrand (pricing) game between the providers. We characterize the inefficiency (price of anarchy) due to strategic pricing to be 2/3. Surprisingly, the price of anarchy for the multi-class setting is the same as for the single-class setting.     

A kinetic investigation of butyl acrylate polymerization

An experimental investigation of the kinetics of the bulk free radical polymerization of butyl acrylate initiated with 2,2′-azobisisobutyronitrile (AIBN) was conducted at 50° and 60°C using two initiator concentrations. Conversion levels were measured by gravimetry and were independently confirmed using replicate runs. The experiments, conducted in glass ampoules, were performed over the full conversion range. A mathematical model for process simulation purposes was developed. The model was able to predict conversion at the two temperatures and initiator concentrations, thus providing a better understanding of the butyl acrylate homopolymerization kinetics.     

Preovulatory follicle characteristics and oocyte competence in repeat breeder dairy cows

The varied and elusive etiology of repeat breeding (RB) in dairy cows necessitates evaluation of oocytes and follicles, which have not previously been assessed together. Accordingly, we evaluated characteristics of preovulatory follicles and the competence of oocytes in control (CTL) and RB cows. The estrous cycles of 35 cows (18 CTL and 17 RB) were synchronized using PGF_2α and estrus detection. Cows with a corpus luteum were treated with PGF_2α and, 14 to 15 d after a visible behavioral estrus, they were administered a second PGF_2α, followed 48 h later by follicular fluid (FF) aspiration of the preovulatory follicles. Estradiol (E₂)-active preovulatory follicles did not differ in diameter between the 2 groups of cows. However, FF of RB cows had higher E₂ concentrations than that of CTL cows: 1,854.9 and 1,073.6 ng/mL, respectively, but similar androstenedione and progesterone concentrations. In the second part of the study, 14 consecutive ovum pick-ups (OPU) were performed in 5 CTL and 5 RB cows, at 3- to 4-d intervals. The RB and CTL cows did not differ in average numbers of follicles available per cow per session (7.1 and 7.3, respectively), oocyte recovery rates (42.2 and 44.1%, respectively), or cleavage rates (57.6 and 63.4%, respectively), but blastocyst production was markedly less in RB than in CTL cows (12.5 and 29.2%, respectively). We conclude that part of the RB cows' etiology occurs at an earlier phase of folliculogenesis, thereby impairing oocyte competence, and subsequently reducing the probability of normal fertilization, which diminish embryo vitality and development.     

Interrelation between gold and tin: A historical perspective

The historical evidence for the occurrence of some tin in gold objects and some gold in tin mini-ingots from various parts of the world has been discussed. It has been shown that their presence in each other is not intentional, but is due to their primary metal extraction process used. Both gold and cassiterite minerals were obtained as alluvial placer deposit in ancient and medieval times. Evidence for the simultaneous occurrence of gold in the same vein or alluvial placer deposits in various parts of the world has been presented. This type of deposit could be concentrated to either a cassiterite-rich or gold-rich concentrates by panning, Even the most efficient panning process used in those times, would have resulted into some amount of gold in cassiterite concentrate and cassiterite in gold concentrate. Such concentrates would give rise to some gold in the extracted primary tin, and some tin in the extracted primary gold. If tin bronze was used for making alloyed gold containing higher amounts of copper, at least a part of tin present in the alloyed gold might have originated from it.     

On the magnetizations of the phase in alnico alloys

The electrochemical properties of the Alnico alloys are shown to be sensitive to their state of precipitation. These properties thus are used as an indirect means for evaluating the individual properties of the ferromagnetic phases in these alloys. Results are then compared with recent findings and are shown to agree reasonably well, particularly in the case of Alnico 5.     

Influence of fault arc characteristics on the accuracy of digitalfault locators

This paper proposes a time domain model of a fault locator with special reference to fault are nonlinearities by applying the MODELS language of the EMTP. It has been found that an impedance relay type locator is significantly influenced by the fault arc nonlinearities, while the current diversion ratio method is not influenced. This validates the advantage of the current diversion approach over the impedance approach     

Recent findings in open pit optimization

ABSTRACT

This paper reports on research in which pit designs using the Lerchs-Grossman and Moving Cone Algorithms were individually compared with those of the Dynamic Cone Algorithm. The comparisons wore on the basis of total final pit economic values. Details of the study are described and the results obtained discussed. The results showed that each algorithm in the pairs tested, gave several higher final pit economic values than the other. It is concluded that a correct approach to open pit optimization is to use several different algorithms and then select the beat valued pit from among the resulting designs.     

Effective use of reducing agents and nanoparticle encapsulation in stabilizing catechins in alkaline solution

Catechins are an important class of dietary flavonoids with promising use as therapeutic agents due to their potent antioxidant activity and diverse biological properties. However, catechins are highly unstable in alkaline solutions, such as those present in some biological fluids and experimental protocols. In this study, we optimised, evaluated and compared the effectiveness of the reducing agents ascorbic acid (AA), dithiothreitol (DTT), tris(2-carboxyethyl)phosphine (TCEP), as well as encapsulation in chitosan–tripolyphosphate nanoparticles for their potential to protect (+)-catechin and (−)-epigallocatechin gallate from degradation in potassium hydrogen phosphate buffer (pH 7.4). TCEP provided greater protection than did either AA or DTT against degradation. Combining AA and TCEP provided even greater protection than TCEP alone. The levels of (+)-catechin and (−)-epigallocatechin gallate remaining after a 24 h incubation in the presence of AA and TCEP were 88.3 ± 0.1% and 73.4 ± 2.5%, respectively, compared to 19.2 ± 1.1% and undetectable levels, respectively, in their absence. Encapsulation in chitosan–tripolyphosphate nanoparticles protected the catechins. It took 8 and 24 h for the non-encapsulated and encapsulated (+)-catechin, respectively, to degrade to 50% of their initial levels, and the corresponding values for the non-encapsulated and encapsulated (−)-epigallocatechin gallate were 10 and 40 min, respectively. These results demonstrate that the reducing agents TCEP and AA, and encapsulation in chitosan–tripolyphosphate nanoparticles, have a role to play in the in vitro and in vivo stabilization of catechins, respectively.